Yes, you can add them, they’d be set up as a second Sonos ‘room’, and grouped with the first room for synchronized playback. 

Worth is something you need to determine. It would likely be ‘worth it’ to me, but not ‘worth it’ to another person. Fortunately, Sonos and other resellers have return policy, so you can test it, and make that determination on your own. 

Appreciate your opinion Bruce!

With that big a space you might be better off with a Sonos Port feeding a multi-channel amplifier and larger conventional speakers.

Adding Paired Fives and a Sub would be a big improvement. In that space you might want three or more sets to fill the space well.

Thanks for your thoughts