Here is my set up:

04 Patriot VFT 80% 72lbs draw
27" draw
350 grain gold tips
shooting 290 FPS (average)

My question is if I go to 65% letoff would I pick up any speed? If so, how much? roughly.

Not much. Maybe 5 fps or so. Performance isn't a biggie. It's a matter of preference, really.

I prefer the feel of 65% letoff. I like the few extra pounds of resistance because it keeps my back muscles involved in the shot, makes it a bit harder to torque the string and those things combined make my shot more accurate. I really HATE the feel of the 80% cams when I have to let down. It's very hard for me to let down a high letoff bow.

I agree with Auther,65% just feels better.

I agree. I've changed modules on my Martin and last year on my Pearsons. From 75% to 65% on my SlayR got me about 4fps. On my Pearsons I changed from 85% to 75% and then 65%. Total gain was around 4fps. Not enough to change unless I really wanted more holding weight.

That being said, if you can just change a module then it might be worth a try just to satisfy your curiosity. Modules generally cost $15 or less. Maybe you'll like a bit higher holding weight. It often promotes better accuracy giving a cleaner release.