2nd Angelo's words: whatever tool works for you, use it.
That said, the latest version of Vegas Pro (v.11, 64-bit, with GPU acceleration enabled) has been a headache for a couple of my clients: instability, no appreciable GPU acceleration, lack of support from Sony. While Premiere Pro has its own share of issues, its stability is generally good, and so are community support options; GPU acceleration is awesome.
Alex Gerulaitis
Systems Integrator
DV411 - Los Angeles, CA