disclosure. I have owned and gigged a Buster 200, and I have had a month long trial of a Super Bassman 300 (not the 100T).
So, having said all all that, I would suggest that because they both have basically the same tone stack, the Buster and the 100T will have similar tone ranges, particularly on the Vintage channel of the 100T.
Then again, as you probably already know, the 100T brings some interesting and potentially useful features that the Buster does not have like a second, "overdrive" channel that also offers a more modern tone with sweepable mids as well as bass/treble "boost" features. The 100T also has a pretty nifty 25w mode for lower volume use. It also has the option of a no speaker, studio recording mode which would be a major no-no for the Buster. The Fender also has a user bias function for running the tubes either a bit "hot" or "cold" (or just right). Also, one is brand new design, and the other is a 20-25 year old design (not that that is any problem in general).
So, lots a newer features come with the Fender. But if you are happy with your Buster, and money is any factor in the decision, I'm not sure why you'd get a 100T.
If you really wanted 2 all tube amps, it might make more sense to look at something with a bit different tone profile like Ampeg, Orange or Trace.
Of course, all of this is just IMO .. but you asked.