Arceeguy:
I've owned a gas torch and a tig/arc (Thermal Arc 135) for several years. I never wanted a mig as I didn't like all the moving parts. I've welded stainless with my tig...gorgeous welds. However, as far as welding in tight corners, the tig cup needs to be sized properly in order to get into those areas. This could be a problem with tight pipe angles in bike frames. For welding bike frames, I would probably use gas brazing. A properly brazed weld can be many times stronger than a traditional metal to metal weld. If you can find both tig/arc and gas at a reasonable price (Craigslist?), you'll certainly have all the bases covered.