I've gone back and forth between Swiftkey and Swype a few times...but always ended up sticking with Swype because once I got used to it, I hated not having the ability to trace type, even though I recognized Swiftkey was probably superior in most other facets.
Trying the Swiftkey Flow beta now, and so far so good. It really seems like the best of both worlds. I think it still needs a bit of refinement yet, as the actual trace typing isn't quite as smooth as it is on Swype, but I'm happy with it and will continue using it.