I dunno about that, doesn't sound like a fair exchange.
Yeh, but at least you can exchange the massive guns you don't like for something else. There a lot of times I'd rather have a common Ti than a unique Frz.
You can up the amount of common you get if you want. Go from 12 to 20, or something, but more than that would(in my opinion as a gamer of depressing amounts) be too much to handle.