Unfortunately that compares to over a thousand hours of BTV and MP experience, so take this as a familiarity biased comparison, honest as I will try to be.
The 1600 uses one tuner for OTA HD and the other for s-video from a Directv H20 locked at SD.
I find the other components of Media Portal meet all my needs, music, pictures, video library, weather etc.
Recently Snapstream discontinued Beyond Media so my current system uses Beyond TV and Media Portal exclusively.
Feature wise, I preferred the combination of those two programs over Sage TV and its interface the last time I tested it.
For that test I only tested the default skin, never installing the Sage MC STV.