I have used this engine many times this year and have had the chance to compare it with the 150 HPDI on the same boat during a couple of RIB tests.
I don't have a bad word to say about it, it is very smooth, with lots of mid range grunt and sounds great and the fuel consumption has always been very reasonable. When compared to the Yamaha's HPDI it is a little slower to get off the mark but not by much and as always the two stoke/4 stroke argument is always low end grunt V fuel consumption.
The only reason I notice the difference really is the fact that I have driven both side by side on timed runs.
If I had vast sums of money I would buy the HPDI, in the real world I would buy the F150.
Working for a sea school we are often asked for advice on engine choice, we always try to give honest advice and I would say for everyone in the market for a Yamaha 150, 90% have gone for the F150 over the HPDI.
I know a number of people who use this engine including some commercially, I also do some work alongside a Yamaha dealer and have never heard of any problems with the F150.
Of course the only way to really see what it is like is to use one.
As always, engine choice is personal preference but if was in the market for a 150 4 stroke the F150 would be at the top of my list.