My cartridge and p-stage arrived yesterday and I was able to set them up last night. Both items seem to mate well with each other.
In general, using a p-stage is a much better match with the Rotel pre-amp. The built-in stage didn't have enough gain for even the Shure M97xe MM so I'd have to turn the volume up pretty far to hear it, resulting in a little hiss. Running this setup into an Aux section works much better. Its very quiet.
The cartidge is very smooth and detailed and the p-stage has that nice tube liquidity to it. Neither piece is broken in yet, but they are already a distinct improvement over the Shure(which is still a great entry level cartridge). The AT is a little thinner sounding than the Shure, but more than makes up for it in detail, soundstage and timbre.
The whole rig sounds really great. The mass of the TT provides tremendous weight and solidity. I'm very happy with the way this all worked out.