I understand optical can't do more than basic Dolbly Digital 5.1 That was never the question. I even said in my original post that obviously I have to use HDMI for DD+. I also stated I understand I have 5.1 and not 7.1. There are other advantages other than the extra two channels.
"Dolby Digital Plus as implemented in Blu-ray Disc features more channels, less compression, and higher data rates for a warmer, richer, more compelling audio experience than you get from standard-definition DVDs." -- The more channels is just ONE benefit; and one I am not asking about in my post. I am interested because of the less compression and higher data rates. Ideally I would go with TrueHD but DD+ is still an improvement in this area. You can use either on a 5.1 system btw.
I am not asking about ARC, I am aware of its issue. And I do have the rear speakers...I have a 5.1 system..
I am asking about utilizing the other benefits of DD+ because I get DD+ via VUDU and I want to utilize that for my 5.1 system. Please read my post carefully. Thank you