Hey @Louz0r, welcome to Sonos Community!

I was wondering if the shape of my room would be OK to upgrade the back surrounds to Era 300’s.  The TV with ARC is 14’ in front of the couch.

I think I would need to invert them on the wall but any feedback or ideas would be appreciated.

The shape of the ceiling might affect the sound experience in a negative way, more likely when playing Dolby Atmos content. How is your experience so far while playing Dolby Atmos content, in your current setup?

Bare in mind that if you place the Sonos Era 300’s in inverted position, you will not be able to complete Trueplay tuning, as this has not been implemented yet.

There are several threads in our Community in regards to speaker placement and more specifically the Sonos Era 300’s as surrounds, feel free to have a look.

I would recommend purchasing directly from Sonos.com. You can give it a try and if not satisfied with the outcome, you can return the products and receive a full refund with our Money Back Guarantee. 

Side question - I currently have 1 sub to the left of the TV facing the couch and 1 sub placed behind the couch for some added bass feeling.  Would it be better to have both sub’s by the TV (one left / one right) instead of the one behind the couch?

I believe you should leave them as they are, the bass is better distributed across the room when the Sonos Sub’s are placed at some distance.from each other.

With my reply here, your thread moved at the top of the latest activity list, maybe other members of our Community with similar setups can provide you with some feedback.

I hope this helps.