The Render at Maximum Depth should allow the 10 bit. I'd expect the Depth to reflect this, but maybe not. Have you tested an export yet?
Thank you for responding. Yes, I exported test files from Premiere and After Effects, and compared the files to the source sequence using scopes and a difference matte. The After Effects CS6 32bpc export showed no differences to the source sequence at 0.0% matching tolerance. The Premiere Pro CS6 export was different from both the AE file and the source sequence at matching tolerances below 0.5%, but was the same as an uncompressed 8-bit AVI at 0.0% matching tolerance.
That's one way, I guess.
You can also open the export in KM Player, right click the screen and go to Media Info...
It'll just tell you the bit depth.