We have a smaller boat
(27 feet) that had a 10ho Volvo, saildrive
and original folding prop. We replaceed the folding prop with a max prop and it was undeniably the best thing we have ever done to the boat.
The folding prop has to work
in forward and it has to rely on centrifugal forces in reverse. Bottom line is that it is a compromise.
We used to get 3.5 knots in forward and marginal performance in reverse. Around here we sometimes can get 1.5 knots current
during flood tides.
Now we get 5.5-6 kts in forward and reversing is like throwing out an anchor
. Reverse performance is almost as good as forward.
Do it - You won't regret it.