I have used Thunderheads for years, no problems at all. I recently switched though, because I went to carbons, and I could not get them to spin test true with UBARS. They were fine without them, but I didn't want to take a chance. I switched to Wasp, only because their blades are a bit thicker than Muzzys. Muzzy's are a fine head, though, and any one of the three that I mentioned should do the job just a well as the other.
Trebark