Some thoughts on the topic...
1. I don't believe that HUD stats by themselves can make anyone a good player. At least when I used trials of HM2 and PT4 some time ago it didn't improve my results. I realized that I had many gaps in my own play and knowing opps stats couldn't help me much. However, leak tracker in PT4 helped me a lot, but it's about post game analysis, not about online support. I'm convinced that a good player will beat a fish at a distance even without any software tools.
2. If HUD should be forbidden, then what about notes? With some extra efforts notes can be used to track and keep basically the same information about opps as HM or PT collect.
3. And last but not least, I'm not sure it's really possible to ban gathering stats on your opps. In the worst case there is always an option to transfer your hand history into the tracker after poker room client is closed. Then while playing you could manually search for your opp and his stats on a different computer or even mobile gadgets. Anyway, I'm sure that those who want will find a way.