I have 2 x Play:1s as surrounds with an original PlayBar.

But do you know if it works with the new Beam, Ray and Arc sound bars ?

From the Beam Gen 2 FAQ

Which Sonos speakers work as surrounds?

A matching pair of the following speakers will work as surrounds: Era 300, Era 100, Sonos One (including SL), Sonos Five, Play:1, Play:3, and Play:5 (Gen 2). You can also use Sonos Amp to power in-wall, in-ceiling, or other passive speakers as surrounds.

I think the cheaper speakers are great as surrounds because when bonded with a soundbar the more advanced features (voice control, line-in, Bluetooth, Airplay) of other speakers aren’t available. To some extent you don’t need those features because you interact with the soundbar directly, but line-in availability would be nice.