I think capacity really comes into play on the higher c rating packs. If you look at the discharge curves they really dump after 80% discharge when running at the higher amperage loads. So, if you are running a 5000mah 25c pack at an average of 14c then you better not exceed 3900mah consumption. The discharge curves seem to flatten out with the higher discharge rates but the useful capacity also drops off. So, maybe a 25C pack really needs to be 10-15% more capacity than a 15C pack in order to not run short.

I agree that the power curve is very different and since you are running the more powerful pletti I'll bet that the effect is even more exaggerated for you. On my Dualsky I really see the difference. I have about 6 flights on my 25C packs and at first I found it uncontrollable because I was flying it like my 17C FP's. I adjusted the way I fly and try to fly airspeed vs throttle setting. That's hard to do but because the throttle curve isn't quite right. However, I really like the power and find that I have what I need, as long as I don't use up too much up front. I am thinking about setting up a different model type for 25C's so I set up a different throttle curve and maybe change a few other things. It is like putting a different powerplant in the plane.