I don't know if I believe that rep. because the "2" reps I talked to at Onkyo thought the surround channel info should stay in the surround channel speakers and not the surround back channel speakers. Then I found the info in the NR5100 and NR7100 manuals. I've yet to get a call back from them with a resolution! Great support.
That's up to you, but it didn't sound that good coming from just the surround back speakers. Hek, they should had just put the surround channel info into all 4 surround and surround back speakers. That would had been better for sure. But also keep the Direct mode a "DIRECT" mode and keep the surround channel info steering correct!