ocaddict,
I too have both a PVR508 (via S-video) and a 6000u receiver (via component and S-video) imputed into my Mits TV. I also have a universal remote (MX-700) controlling both receivers independently, along with my TV, VCR (Mits), Stereo/Amp (Yamaha), and DVD Player (Yamaha). I love my MX-700 remote, especially the ability to programmed via the computer. There is free software (MX Editor) that allows to program everything you need, make on-going adjustments, etc..., and download the configuration to the remote in a matter of seconds.
I am able to control the two Dish receivers independently by changing the "address" on one of them. My 508 is address 1 and my 6000u is address 2. I have my complete configuration uploaded to www.remotecentral.com, for review and downloading.
I like having both receivers hooked up to the TV, because it gives me the ability to record one thing (except HD) and watch another. This is a functionality that was missing from the single tuner 508.
I too live in Atlanta, so if you would like further information about my setup or remote, please send me a PM. I can give you a call.