Well, I know what's "supposed" to work. That's why I asked if anyone had actually tried it!

Thanks for your input, but I thought that between the thread title and the question "Has anyone tried something like this?" I was specific enough about seeking actual experience as opposed to E* recommended practice.
The key to my question lies in the DP/Legacy adapter. In particular, the adapter must (by definition) make a DP LNBF (& switches, if any) look like legacy gear to a legacy receiver. Therefore, it may look that way even if it is behind an SW21 switch. As I understand it (aside from E* saying "don't do this"), the main reason why DP & legacy LNBFs haven't been combined is that the legacy adapter must be right near the receiver. Most people's switches are near the dish, not the receiver.
What I am proposing as an experiment (see thread title

) is bringing the 2 signals (DP & legacy) all the way to the receiver, then running the DP line through a DP/Legacy adapter (at which point it looks like a legacy LNBF) and then (at the receiver) adding a legacy SW21, switching what at this point look like 2 legacy LNBFs.
Why try this? Now that we know WCBS-HD is not going to move off 61.5 anytime soon, I'm considering putting up a (very hard to reach) dish for 61.5. I'd prefer to use a DP LNBF, so I'll be ready to change over. On the other hand, I'd prefer not to swap out my other LNBFs & switches until the DP44+ is out.
So, the question is whether anyone else is adventurous (crazy?) enough to experiment with an (admittedly unsupported) unorthodox setup.