The Taig can handle stainless just fine. You will have to use a much more conservative feedrate than if you were milling aluminum (of course). With stainless you need to keep your tools perfectly sharp and use a flood cooling system to avoid work hardening the material.
The next thing to consider is accuracy. When properly set up you can get the Taig mill down to around 0.0005"~0.001" backlash. The lathe with a 3-jaw self centering chuck can be trued to 0.0005" TIR, and with a 4-jaw chuck you can get it better than that.
So if your application fits within the physical limitations of the machine and you don't need a very high speed production then the Taig would work well.