To the best of my knowledge, Poker Tracker is fine in all versions. The folks at PT have said they work intimately with the sites to insure PT isn't used unfairly.
In a nutshell what PT does is act as if you had perfect memory, and unlimited historical bookkeeping skills. It will remember the last hand you played or one 7,000
hands ago. It will keep track of your finances, to a point, on the sites they are currently importing. It will show you your tendencies, and from that YOU will determine if they are leaks or not. It will NOT find a leak and show you that leak with a large red flaming arrow.
Reading through the PT forum today shows that beta 18 is largely being applauded, and the nature of the problems today seem to be with the newly added auto-rate function. Even then it seems that the problems are mostly clarification issues on just how to implement the feature.
Apparently MOST of the crashing issues have been fixed, and focus has turned to providing PT3 with more and more of the functionality of PT2. No new sites were added, and none seem to be planned for the next beta which might be an actually fresh release, PT3 build 3.
Many folks swear by the HUD. They make many decisions based on what that HUD is telling them at that instant. I don't use it that way primarily because I haven't found a nice way to display the stats while actually playing. In my case I primarily use PT3 to help me keep track of my money, and help me find my leaks. Leak finding would be nearly impossible without something like PT3 or Holdem Manager.
Many folks have ported the PC version to their MAC's via
linux. I am not a MAC guy, but it seems they are running a Windows emulation and then PT3 on that.