I have lurked here for some time and have to disagree with Jeff_H and how he chimes in as a know it all on things he has no expertise at all. If Island Packets were terrible boats, why can't you find a current or past owner with anything negative to say about them other than a few small compromises that are in any boat?
I think that your assumptions are based on a very false understanding of what my comments are based on. I do not consider myself an expert and so would not apply the term 'expertise' to my comments, but my comments are based on my experience with the boats that I am commenting on. In this case, my comments are based on the fact that this is a boat that I have sailed in a range of conditions, and observed in a broader range of conditions. I wrote up my sailing experiences with these boats in detail when they happened and you should be able to find those comments.
But for background, for much of my adult life, I have been invited to sail on boats to help their owners get more out of them. This has given me a chance to experience a lot of different boats first hand, and to develop a relative sense of how they behave relative to the other boats that I have sailed on. I like sailing on boats which are very different than the boats I normally sail. While I have owned boats that range from wooden 1939 full keeled cutters, to comparatively high performance cruisers, I have no dog in this hunt when it comes to commenting on particular makes and models. If I don't have direct experience, my comments will generally note that.
In the case of the Island Packets, I have been invited aboard by Island Packet owners who were very dissatisfied with aspects of their boat's sailing abilities, and were looking to learn to sail them better. They loved the interior volume, and comfortable cockpits, they liked the boat's slower roll rates, and they were mostly pleased with the build quality, but they were sorely disappointed with how the boat sailed.
When I do one of these efforts to coach an owner on how to sail their boat's better, it tends to be somewhat experimental in nature. Anyone who has been through this with me knows that I come aboard with a pocketful of 3x5 cards and make notes on boatspeed through the water, apparent wind angles and speed, true wind angle and speed if available. GPS courses vs. compass courses and so on.
If the boat does not have luff and leech teletales I drop the sails and put them on. I mark the center spoke of the wheel, jib lead positions, and tape an inclinometer to the bulkhead, and then go to work.
I start by getting to a baseline set of adjustments that match textbook settings (telltales flying) and then begin experimenting from there with pointing angles vs speed and leeway. I observe note things like the rudder angle, aeration of the wake, heel angle and so on. I go through multiple rounds of that making notes until I have a sense of the boat's behavior, and then start making sail adjustments and repeat the process until I have a sense of what it takes to optimize the boat for that windspeed and point of sail. I also try to bench mark performance with boats around me.
In the case of the Island Packets I was on, there were a number of complaints about their sailing ability that we were trying to explore. These included poor pointing ability, lots of leeway and weather helm in a breezes over 15 or so knots, and poor light air sailing ability (which they defined as being under 10 knots, a windspeed that I would have called moderate breezes).
We worked on the pointing ability in mid-range windspeeds and concluded that the owners often were trying to pinch and that the boat got a better VMG powered up and not trying to point as high. Even when optimized, the IP's VMG was not very good as compared to similar sized and coastal cruisers, and I doubt that the benchmark boats were as carefully optimized as trimming as aggressively as we were.
Dealing with weather helm in a breeze was a bit more difficult. The weather helm seemed to largely heel angle generated, and that the rudder angle required to keep the boat tracking was slowing the boat down. We experimented with 'fisherman's reefs' (lots of twist), blading out the sails, and ultimately with reducing sail area.
Twisting both sails flattened the boat's heel angle some and helped with weather helm, but at a noticeably reduced speed through the water. Blading out the sails, also reduced weather helm some, and reduced heel less, but still hurt speed. In the end, over 15 knots the best performance and helm balance came from a small reduction in sail, and moderately, but not radical flattening of the sails. That is a pretty low windspeed to have to shorten sail for a boat that is billed as an offshore cruiser. And even at the most optimized, the speed was still slow compared to other boats around us, and frankly was not all that much fun to sail, even though we had picked up close to a knot from where we had started out.
My other observation was that the boat was surprisingly rolly reaching in a short chop, and seemed to collide with waves more violently than I would have expected when beating in those conditions.
The light air issues were two fold. First of all, it was very hard to get the boat to reliably tack through irons in wind speeds below 10 knots. (The owners said, they almost never sail in winds below 10 knots on that boat, but might if we could make the boat sail better.) The owners said that they tended to start their engine to push the bow through and then cut it again. Even so it was hard to keep the boat from swinging past the new pointing angle, which made for a harder time cranking in the sails, (the winches seemed a little low on mechanical advantage for the loads, at least as compared to what I am used to). We ended up improving the tack by tacking slower than they had been trying to, rolling in the genoa until the clew was a foot or so aft of the jibstay, holding onto the new windward sheet to start the bow to swing through then releasing the furler line and windward sheet once the bow was a few degrees on the new tack and pulling in the sail aggressively. The helmsperson also reversed the helm sooner than they had been to keep fro overshooting, which was a delicate balance. Collectively that helped a lot, but was a lot of work, and frankly was too finicky for the owners.
The bigger light air issue was simply keeping the boat moving at a reasonable speed in winds down around 5 knots. We were not able to do much for light air performance, which based on my observations was dismal by any objective standard. In those conditions, we got our clocks cleaned by a Tayana 37, which I don't think of a sterling light air performer. Proper halyard, and outhaul tensions, along with proper sheet lead, traveler, vang, and sheet adjustments helped a little, but not enough to satisfy those owners, or meet my standards for what I would consider a reasonable sailing performance in lighter stuff.
I understand that you and many IP owners may find these characteristics satisfactory, and are very happy with your boats. That said, not all IP owners would agree with you about their boat's sailing abilities. At least based on my observations, I stand by my observations of IP's sailing ability relative to other boats of similar sizes and purposes. While these boats can be made to sail better than they are often sailed, I stand by my statement that if you are buying boat because you enjoy sailing, then the IP is probably not a great choice.
I hope that adding the basis of my comments, helps you and others reading this discussion understand where I am coming from, filter out any bias on my or other's part, and perhaps explain where you differ based on your own experiences.