She's a nice dog. I used to breed pits some 25 years ago. So I know a nice pit when I see one. Problem is, dog genetics are complicated. When you cross breeds you can never be sure what you're going to get. There's a reason pro breeders study generations of a dogs bloodline before deciding if it's something they want to bring into their line.
Personally I'd look for a nice male pit with a good temperament if you're set on breeding her. The pit/rot crosses I've seen are nice looking dogs. Not as nice as a good pit or a good rott imo, but to each his own.