Bob - The SWM8 only needs two inputs to work, not four. And the OP says his dish has two outputs, which implies a 2 lnb dish. Your comment about aiming sounds familiar, but if that's the case, how does the dish handle two receivers? With an SWM8, the dish would think it had two receivers connected, one requesting odd transponders and one even transponders, both from 101. Won't that work?
Well for starts I keep seeing a PI21 needed for a SWM8. It needs a PI29 to work properly, also, I see using the 99/101 slot working but I'm curious how long the switch lasts only sending 2 lines voltage vs 4? Could this cause any damage to the SWM8?
OP, stick with the D12. Going to all this trouble for the same result a D12 will get you is more of a hassle without a 100% promise to even work.