He got it to recognize five satellites, but only used a DP21 to straddle the DPP44 and single DP dish outputs, which would not permit total agility, meaning that you couldn't have one tuner simultaneously tuning one transponder from a satellite connected to the DPP44 and another from the fifth dish.
I have searched for evidence of the existence of a DPP21 in vain. I tentatively conclude that product does not exist.
Since the 129 slot has an elevation angle of just 20 degrees here in Washington DC and maybe even a little lower in New England, it doesn;t seem plausible that DISH will assign any unique national programming there, so it looks like I will be just going with 61.5/110/118.7/119 for my four satellite system for this building. Our HDTV locals are also on 61.5.