Not sure of the info you received, but no matter the setup you will always be able to watch/record 5 channels simultaneously. I have the Genie plus an H25 so I can watch/record 6. I like having the H25 as a back up since the Genie would be the only satellite receiver if you have Genie and clients whereas I could at least watch one DTV channel if my Genie died by putting the H25 in its place.
Clients are NOT satellite receivers so if you have a Genie and 17 clients you will still be able to watch/record 5 channels on the Genie.