I'll be happy to help out with the races when you are ready. I'm still refining my first race, but that's partly because they're monstrous humanoid with a level adjustment. These shouldn't be nearly as hard.
The general rule I have about magic in books is that the main characters are heroic, i.e. level 6 and above, where the power level begins really ramping up. In general, it's fairly easy to keep things balanced with allomancy. It's something that already balances out with it's own drawbacks and a reliance on the laws of physics. I'm working on the crunch slowly with a friend of mine, but I'm considering posting something here about it. (In fact, I should go do that now.)
At the very least, allomancy lacks the ability to alter the world with inexplicable powers from some occult source.