If it's stainless, it's crap. Good enough to hang on the wall. Not good enough for anything else. Quite dangerous for active use as a weapon for ANY kind of training. And by dangerous, I mean it is dangerous to the user and those around him.
If your goal is to cut things with your sword, check into at the very minimal level a Paul Chen Practical Katana or a Practical Katana Plus.
If your goal is to goof around with your buddies, then buy a decent shinai and save yourself the trip to the emergency room. Or if you must buy yourself a bokken and at least the injuries will be limited to broken fingers, empty eye sockets, and the occasional concussion.
If your goal is to do solo practice forms, your best option is to pick up an iaito from Swordstore.com or Bugei.com.
In any case, you should seek proper instruction. Metal swords are a lot like guns. They can maim and even kill accidentally. And don't tell me you know enough about what you are doing to not need instruction. Nobody who knew what they were doing would ask if stainless was a suitable metal for a training weapon.