I shoot my UT at 30 draw and 68 lb. Arrow 390 grain speed 292 fps. One brass nock, ture peep and two leeches on the string.
The difference with let off between 65% and 75% is 1 pfs, 65% let off to be faster than 75% let off. 350 grain arrow at 68 lb flew at 308 fps.
Spiral cam wil be about 5 faster than cam 1/2. Remember, when you by cam 1/2 make sure you choose the cam set up to shoot at the end of the cam. They shoot faster. My cam is set up at E position, where it A is the shortest and F is the longest. For more answers you can go to hoyt.com forums.
Vodek