I'm running the NVidia beta driver (195.39) on my GeForce 9800 GTX+ 512 and they're running fine.
I have had some incompatibility issues with my Viewsonic VX2000 monitor at higher res, so I thought maybe the newer drivers would address that issue, but it did not.
You mention that the 9800 series cards have lost some "oomph" with the latest drivers.
That fits my problem. Ever since upgrading the driver last December, my VX2000 monitor displays "noise" when running at higher (greater than 1280 x 1024 @ 60hz) resolutions. I never had the issue with the older drivers (a version released back in Oct 2008 came with the card).
I had been using the old drivers on my Win XP machine, but after installing Win 7 (dual boot on the same machine), I had to use the latest driver, and I had to bump my screen res down to 1280 x 1024 @ 75Hz to get rid of the noise.
As for TS, it doesn't matter. I have not seen any performance increase or decrease with any of the driver updates.
FW