Another advantage is that when you touch the hull you don't get
covered with ablative paint... This all raises a serious question in my
mind as to whether ablative antifouls are that useful -maybe they are
best suited to smaller boats that never really get going fats enough to
displace the slime? Any thoughts?

None comes off but that only means it builds up and you'll be scraping one
year. Your thoughts on ablatives being better suited to smaller boats with
less speed is the opposite of what I would consider the way to go. BTW unless
you have a power boat I don't think going "fast" in any sailboat is fast enough
to remove slime. You gotta wipe it off.
BTW most manufactures do not recomend any thinning of bottom paint.
S/V Express 30 "Ringmaster"
Trains are a winter sport