Dave you seemed OK to go on a 1500+m daysail with me and my spade rudder a few years back
Was it because just half of it was out of helicopter range?
Sure - I sail boats with spade rudders and partial skeg rudders over oceans all the time.
All the hype about full keels v. fin keels is ill informed. People simply don't understand the issues. Everyone thinks he or she is an engineer after reading a few magazine articles and a book. If you have enough faith in professionals to drive across a bridge you should believe us when we tell you that a fin keel is a good thing.
I'm not poking at you, outbound, at all. I see the research and study you have put in, as have others like Jeff_H, and most importantly the occasional "I don't know" when, well, you don't. That's well educated, open-minded behavior.
EVERY boat, like every commercial ship and warship is a series of compromises. Some compromises are good choices and some are not.
On the newer three digit IPs the Full Foil Keel(R) provides very shallow draft boats. For many cruisers, especially those on the US East Coast, that is a very attractive and desirable characteristic. The trade-off is that pointing under sail is not as good as it could otherwise be (and is on the older two-digit boats). Most cruisers can't or won't tune the rigs on their cutters (like IPs) to point well either.
On the other hand, passagemaking is a small portion of the time we spend aboard for most cruisers. IP is an extremely comfortable boat. I like sailing fast but at some point there is some merit to saying that you are okay with taking 10 or 15 or 20 percent longer to get somewhere as long as you don't spend all that extra time getting pounded by weather. It all becomes very stochastic.