"Did somebody paint a big bullseye on Island Packet sailboats or what?"
Yes, Island Packet did when they chose the design approach that they did. Its simply a physics thing; huge amounts of wetted surface, a poorly shaped underbody, and foils, a dearth of sail area and an excessively inefficient rig proportion.
That is not hearsay, its just plain basic physics. And it is easy to quantify the relative impact of that design approach. When you look at the PHRF rating in any Region with light to moderate prevailing winds, the Island Packets are typically 60 to 90 seconds a mile slower than boats of an equal length, and 2 to 3 minutes a mile slower than more normal designs of an equal displacement. Those kind of number are huge difference in speed, and in cruising modes, slower boats generally do worse than their ratings might suggest. PHRF normally spots cruising boats a little time in racing mode, and so while these numbers may do Island Packet a 9-12 second disservice in racing mode but they clearly show that Island Packets are a bit doggie.
And that matches what most of us have observed out there on the water. In reality, my observations sailing IP's and observing 100's of them under sail for decades is that they really do not perform at the low end of the wind range.
While you may be able to crowd a large enough genoa on a Island Packet to close-reach at "3 knots in 5 knots" of true wind, that would result in an apparent wind of somewhere around 7 knots. In the same conditions a decent light air boat, i.e. one that is not a little doggie, without an oversized genoa, would be generating closer to 8 or 9 knots apparent wind in those same conditions and would be moving closer to 5 knots through the water, in other words doing close to the true wind speeds. And that is the precisely the point being made when people say, Island Packets are a little doggie in light air. But not only are they slow in light air, but they also make gobs of leeway compared to boats with more efficient keels.
In the end, what counts is you are satisfied with the performance of your boat, and that is a good thing for you. As such it should not matter to you when other speak of the relative capabilities of the IP's.
But when someone asks for a relative description of the performance of these boats and thier suitability for use in a predominantly light air venue, the alleged offshore capabilities of an Island Packet (I say 'alleged' since the A Offshore rating really does not really define the suitability of a boat for offshore use, just its likelihood of surviving out there) may be relevant for some, offshore characteristics were not the question being asked. What is relevant, is the observable light air performance, and IP's poor light air performance is easily observable by anyone who has sailed one in light air or seen them try to sail in light air.
Jeff, you are right. They are heavy and have low SA/displacement ratios. They aren't made for racing, have a larger tack angle than others, and the full keel adds to the leeway made under sail. They were designed for comfortable cruising, with roominess and shoal draft. In that respect, they are unbeatable.
Sailing on a day with 20 knots of breeze gusting to 25 knots is a real joy while bounding comfortably along while some popular priced, lighter sailboats are tied to the dock, knowing that sailing in those conditions would be challenging and uncomfortable. Pointing ability is not as good as one may desire, but cracking off the wind by 5 or 10 degrees will provide much more speed than pinching too close-winded. I may have to make an extra tack or two to get to the destination and be 20 minutes later than the other boats, but I enjoy the solid feel and comfortable ride.
As far as the Offshore A, STIX and other ratings; they are the best we have currently and as you say it defines their "likelihood of survivability" in the offshore realm..... and I will take that as big plus
for the boats design.
I just object when Sailnetters trash the IP as pigs, etc. when in fact, they meet their design criteria quite well. I'm sure you notice that most people here do not "trash talk" other boats but simply point out commonly known areas of deficiencies in the build. No boat can fulfill every possible intended usage. They are all different, as people are all different.
I don't mean to create ill will here, but honest questions posed deserve honest answers. The OP asked about "light winds" and then gave a range of wind that is more than enough for any IP.
I'll be quiet now.