Some mini-mods might help....
I have a Cougar III with C base cam Nos X cams on it. Although the label says 55-70 # and the cam modules said HL, I only got 66# and about 67% let off. I spoke with Martin about it, and they guessed correctly that I was at the lower end of the draw length adjustment (29", the 2 slot on the cam modules.) They said that being in the lower slots will sacrifice a little bit of draw weight & let off. I got some mini-modules for the bow. 29" is at the max setting on the mini-modules. I now get 69# and 72%+ let off.
I also agree that the Nitrous cams have a very small valley, but it is an easy adjustment & well worth it, as the cams are blazing fast & very accurate when properly set up.