Aside from the features listed above, it seems the best reason to choose T1 over a B is the connectivity with computers. If, like me, you don't use computers in your set-up, a Virus B is a fine instrument.
There was a good thread on Gearslutz where a couple people chimed in to say something like "I've had both and think the B sounds better". I don't have direct experience, but seeing a handful comments like that there and elsewhere drove me towards a B, which I just bought! Arriving soon..tick tock..
I own a TI, and my friend owes a B....I bought the TI because I though the integration with the computer might be something cool......However, I never use it. It doesn't seem to stable as Ashe stated, and it also seems to slow down my work flow. I simply use it as a hardware synth, and I think the thing sounds great. If you don't the extra Polyhony than the B should be fine. Saying that something "sounds better" is totally subjective anyway. I would never sell my TI, as I love the sound. If you want to save money though the B is a fabulous VA.
I personally didn't find the integration very stable at all when I started demanding more than the basics from it. Which is a shame too, cause if it had worked, I'd still have it.
It really varies from person to person though. Some people have no problems.
Discovering TI to its full potential (fx, stomp pedal emulations etc.) would be a nice bonus, plus you won't get bored of it unless you don't like the core sound.