G`morning Raff
When I bought my Vixen it came with a 68 inch GSC. I never did fool around with the pitch but if I remember correctly it flew at MAX high 90`s MPH at about 5500 RPM at 2500 ASL.

I changed to a 70 inch IVO IFA on the recommendation of many folks on this forum. I elected to go with the Ultralite model as my 912UL is a mid 90`s version and may have a lighter drive than later engines. I sent the engine serial number and a/c type to IVO and ordered their recommendation,so I am not sure if it is Patriot blades or not. The prop now has over 600 hours on it, and like has been mentioned, the planetary/motor assembly on these is pretty small and can be subject short life if you are constantly dinking around with the pitch controller!
I would say this is a good low budget IFA setup for the 80 HP engines but, of course with deep pockets and 100+HP the Airmaster is definitely the way to go.
I am always surprised at how much throttle and/or pitch adjustment is necessary on cross country flights, especially in the mountains. The CS and a bunch of cash would take care of that!!
Oh, to answer your question, I can now cruise at 115 or so with the IVO.

I really believe in order to get performance and efficiency out of these small engines IFA pitch really helps.
Good luck with your experiment.
Cheers
Don