I recall reading somewhere about them loading the New Vaquero higher than the standard loads (around 20,000 psi instead of the normal 14,000), but couldn't tell you if it's safe or not, so read at your own risk. I have a Blackhawk, so this is for information purposes only. If you grenade your hand, not my fault.
http://www.riflemagazine.com/magazine/PDF/HL%20246partial.pdf
Another thing to remember, is low pressure doesn't equal low energy..... I've tried the normal (good for all 45 revolver) 45 Colt loads in my Blackhawk, and you know it when you touch the trigger. Clays, Titegroup, Unique, BlueDot, Herco all work well.
You'll probably be more than happy with standard loads though, because Andy has a point about the high pressure loads....they're obnoxious.