I have an 8300 that I've been using on T-mobile network for over a year. I'm running an official release of 4.5.0.81(101), which is what you are all installing now.
If it's like my Blackberry after the new OS install, you will need to resend your service books to get the HTML email to work.
Also, the word I'm getting from some other forums is that the extra weight that this file (the T-Mobile version) has IS for myfavs...the other don't have it (and I couldn't get it for my 8300, since its an AT&T and the software isn't T-Mobile specific).
Good luck!!!