I have a set of Muzzy 4 blade 100 grain phantoms I've been testing out.
http://www.muzzy.com/phantom.htm 
I'm shooting them out of my Mathews Switchback XT
(set to specs by Jerry's Bait and Tackle in Milford, MA):
66 lb / 28" draw
27.5 " Beman BlackMax arrows (custom crested and fletched by me [8D] )
2" Blazers 1 deg offset
At 20 yards I'm getting sub 1" groups and impacting ~ 1 inch lower than my fieldpoints!!
I might try nudging the rest up a smidge higher but I don't know. Has anyone else tried these heads and/or had this sort of luck with them???
I am psyched!