I've got no dog in this hunt either way, but will pass along some info that I have learned about Hevi-Shot. My good friend and maker of Comp-N-Choke, Kick's High Flyer and Vortex choke tubes, Charlie Boswell, has his shop and office on the land that he leases me to farm. I've been in his business regularly ever since Hevi-Shot came out and know that he warrants his chokes for shooting everything on the market, EXCEPT Hevi-Shot. You would be amazed at the number of tubes customers have returned to him over the years that were split or otherwise damaged beyond use by shooters using Hevi-Shot. I have personally seen many of them, and the users admit they were using Hevi-Shot. The stuff is so hard that when it tries to pass through a very tight constriction it sometimes won't make it without bridging and ruining the tube and many times the barrel as well.
Again, I've got no interest in either company, but am just reporting what I've seen. Anyone who wants to debate it is free to call Charlie's shop at 912-829-3936 and hear it from the "horse's mouth".
Stan