Can't say anything regarding the first part of your question.
As for TI+Reaper, here's a brief summary of my experience:
- the good: it works!
- the bad: the latency is huge (as in, ~4000 samples / 100 msec). And because of latency compensation, the same latency applies to any synth you play (not just the Virus). Everything's OK if you draw notes with the mouse, but for live playing it's unacceptable.
Never tried the VC in an officially supported DAW, so can't say if it's a Reaper-specific problem.