One would think it would depend on some other factors as well. My 35 year old 36 footer has a 5' fin keel but is also 18,000 well designed lbs. So it both - points well enough for a cruiser and at the same time is not at all tender
A friend who is a maintenance
manager at a large sailing club and I were making a short easy delivery
the other day so we just talked about this and that nautical and marine
related for a few hours of an easy sail. He mentioned how few days before he was taking some newbie club members out for a sail on the club's brand new shoal keel 38ft Solana. During some wind
gusts when the kids
would not react quickly enough to his commands the boat would heel with spreaders almost touching the water
. He said even he was surprised how tender
it was but then he looked up boat's tech data and saw that it was very light for it's size and it's sail area was large for its weight and ballast. What also surprised him was the fact that the designer
of this particular model was a well known and respected NA from GB (I forget the name but I think he has a Spanish/Italian? last name).
So the jist of this post is that more modern light weight designs would probably do much better with the deep blades while the older more heavier ones can get away with shallower fin keels provided the weight and ballast are well distributed.