For what its worth - I've just jumped off 2012 C4's to 2014 RPM's. I have 8, 10 & 12m. Same sizes I had with the C4's.
I haven't had a lot of time on the RPM's (lack of wind

), but so far have found the wind range pretty much the same as my old C4's. So may give you an idea as what to expect power wise. I actually find my old C4's to slack marginally more than the RPM's (do feel some pull in the air with the RPM) but the RPM is more stable when unhooked. It needs more input to turn than the 2012 C4 and has a good solid reliable feeling to it. Sorry, I havent tried the Fuel but hear the slack line is much more noticeable than the RPM.