upgrade a Playbar or not

Depends a lot on what you watch. I found that l liked the extra width, but the amount of Atmos related content is slim, for me. I gifted my PLAYBARs to others, they were quite grateful.

The upgrade in connectivity was nice for me, as well, since my TV already supported ARC, an HDMI connection, but if your TV doesn’t, the benefits decrease. 

The PLAYBAR, which can easily run S2, is still supported, and is an excellent device.

I would stick with the PLAYBAR for now. The Beam is much smaller in width, and I don’t expect the Arc would be as significant upgrade for you as its cost suggests, unless you feel like you’re missing something in particular. 

I have also been thinking about upgrading to Arc for a long time.
(Playbar-Sub 2gen-2xPlay 1)
My system plays great so it should only be to get a much better sound experience when I watch movies.

Found out that if I were to get a better sound experience, an upgrade of my Play1 was also necessary and preferably to the Era 300.
Then it suddenly becomes very expensive, I am not convinced that the experience will justify such an investment at the moment.

Furthermore, I also think that SONOS will launch a new soundbar this year: Arc is by now an "old" soundbar..
I also think it is possible that this new soundbar will be able to add many more speakers so that you can really get the wild Dolby Atmos experience. (At least that's a hope)