Is the system functional? Operationally, how would converting to SONOS improve your experience? How many rooms does the system support? How are the rooms controlled?

Yes the system is functional. The system currently only runs off the tuner and has wall controls in each room, currently the system supports  a total of 12 zones. the previous owner took all the receivers for TV in wall surrounds.  For home theater I run a Sonos arcs and subs. Instead of going out and purchasing receivers and a wired sub  to connect to the Russound I would prefer to use the sound bars and have the in walls paired to it. 
 

I think 12 zones is over kill and will eliminate sole rooms my thought on zones below. 
 

Zone 1: (living room) arc with port or amp (not sure what to use) to the in wall front speakers and in wall rear speakers 

Zone 2: (basement theater) arc and sub paired with rear in wall speakers and in wall left and right speakers 

Zone 3: outdoor ground floor has two bose in ground garden speakers and two JBL speakers on exterior wall 

Zone 4: outside upper deck 2 outdoor JBL speakers 

In terms of improving experience during a game I can pair the outdoor speakers to the TVs while I am grilling etc it will also allow me to stream music via apps etc 

You might consider hiring a pro.

It’s great that the previous owner took the video, because this RUSSOUND equipment is obsolete with respect to video. A quick and easy audio integration would be to replace current audio sources, such as Tuner, CD, and Tape (if any) with PORT’s. This would not require any RUSSOUND reprogramming, but the device names might not be appropriate.

Note that SONOS soundbars do not support additional left and right front speakers. You could use an AMP to drive left and right front traditional speakers. There will not be a center channel in this arrangement. If the front speakers are close to the TV and image well, a center channel speaker is redundant. AMP can drive surround speakers or you could use SONOS powered speakers for surrounds. SUB can be added to the front AMP or soundbar.

I’d think you might want to try just one Port for the two outside zones, how often would you want them playing different audio?

If you decide you need more individual audio streams from the old system you could add additional Ports to your Russound to support that.

With an Arc there is no need for a Port as the Arc will play the same things the Port would.

If you want to use the in-wall rears as surrounds then an Amp would be needed BUT the surround link is 5 GHz and has limited range. It is intended to be in the same room as the Arc, not across the house. You might work around that by wiring both Arc and Amp to Ethernet.

Maybe save the old gear for background music and go for a full Arc, Sub, Surround setup with Era 300s as the surrounds. Stepping down to Era 100s or a mini-Sub would be an option too.

Thank you for the input. Looks like I will create the surrounds with my existing Sonos products for movies and TV  and tie into the in walls for music and to group the TV sound when a game is on via ports. 
 

Some additional info about the system I discovered today just in case there is other thoughts. 
 

Each Russound zone has a 20 watt/channel stereo amp, so I have 6 stereo amps in each box, total of 18 stereo amps. 
 

Thank you for the feedback. 
 

The wiring shown in the photos is a little obscured, but I think that you have 16 keypads and rooms. Each amplifier can manage four analog sources. The AUDIO AUTHORITY boxes likely distribute the same four sources to each amplifier. You could use one PORT for all rooms, or multiple PORTS. I expect that the RUSSOUND configuration could manage up to four PORTS without any reprogramming.