... My understanding of the situation is that multiple DVRs isn't the problem it's having multiple servers on the same network,
that is to say "Genies" (be they 44s or 54s), that messes everything up. The Genie II (HS-17) is basically just a headless 54
(won't feed a tv directly) that will support more clients and has the wireless video bridge built in .... that's about it.
As far as having additional servers, dishes, etc for campers or vacation homes I don't see it being any more of a problem than
it's ever been other than DTV really wanting that to be considered another account.
As far as keeping an HR-24 in the mix with any Genie (HS-17, HR-44, HR-54) there's no reason I can think of why that wouldn't work.
You might want to check your LNB to see that it's a reverse band 3, because you're at the limit of a normal 3.
It should say 3DR2RB instead of SL3S.