I looked at a used CTS-V or a new SS. It really came down to buying new and have the warranty, and Chevy was not making it easy to by the SS when it first came out. The local Chevy dealership turned me off from buying from them fast.
That said, hopefully you're transmission issues are not only resolved for your sake, but also ours. It seems like two critical components lacking in aftermarket support are fueling and drive train. Fuel has been 'solved' with meth and ecopowerparts fuel upgrade. I would think that in order for this platform to progress from big number power, to large number power; trans and PTU upgrades have to come at some point.