I've been using the GTX 470 since CS5 and it works better and faster than ever with CS6. Even I'm surprised!
Not sure about the GTX 460 but I'm close.
CS6 Production Premium, Win 7
I use the 460 with no noticeable difference between 6 and 5. (I skipped 5.5)
I too used a GTX460 with CS5, CS5.5, and CS6, and had no problems.
I have just taken the plunge and bought a GTX680 with 2GB of memory, and CS6 definitely runs more responsively with this more powerful card. What I did not expect is a general improvement in Windows performance - the monitor looks "cleaner" and sharper. this is obviously subjective!
I also see no noticeable difference between 5/5.5 and 6 with GTX460.
[Moved to Hardware Forum]