If you can live with the limitations and price - maybe something to think about. You can only play spatial audio (Dolby Atmos tracks) if you are connected via WiFi, even though the Era 300 can be connected via an Ethernet cable using the Sonos dongle. Why only WiFi?? And then you have to have either Amazon Unlimited or Apple Music to play Atmos tracks (smells like a back room deal to me). Again, why these limitations? As well, there is no support for MQA files, which could have been incorporated in the speakers fairly easily.
So say you want to setup a stereo pair of Era 300s. For the speakers, stands and dongles - 1204.00 and up. And don't forget Amazon Unlimited or Apple Music if you want to play Dolby Atmos tracks. It could all add up to a pretty penny, and considering the annoying limitations, not so sure it is worth the money.