My boat has never been over 63 even with the Yamaha. I won the Honda and when the gas prices went up I could not pass it up, since I fish tournaments. Yes fuel economy was my prime concern since I have NEVER had speed in this boat.
Honda's are "special" because they run large diameter props with low pitch. (I am currently running 5500rpms and want to get to 6200 since that is where Honda's run best. ) BUT even with the Yamaha 200 ProV I was turning 5800 rpms but still not enough lift to get on the pad behind the seat. With the trim extenders it got me more lift and 3mph more (with both motors).
I don't expect to repower the boat anytime soon since I have seen Honda engine printouts with 7500hrs and more.
I can get another prop but I would like to get the lift situation worked on first.