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!

i use the magnus stinger which is basically the same thing only sharper and yes, they are very acurate... this style of head is very acurate and most importantly very dangerous...
good luck bud.