Buckhunter,
I shot thunderheads for years and think they are a great head. The only thing I didn't like is I couldn't get them to shoot the same as my field tips.
Several years ago I switched to Rocket Steelheads. I also changed bows at the same time. I've had great success with Steelheads. They shoot great for me. Most shots are complete pass throughs. My son and I have taken several big bucks, a number of does, antelope, kudu, gemsbok, hartebeest, impala, warthog and other African game other and not had any problems. At most a blade may bend but I always replace them anyway. Very few animals go over 150 yards and most have dropped in sight. We do pick our shots very carefully.
About the only down side is that the screws holding in the blades are a bit of a challenge for me to work with when replacing blades. I've shot them with both carbon and aluminum.
Good luck and good hunting! Old Buck