The latency is due to the need to buffer the input for multi-room play and isn't going away.  Bottom line, the Sonos line in function is not suitable for live performance.

If there is a brief problem on the network there could be audible consequences. For example, a blast of interference could wreck a packet. Network clients are very aware of this and will request a retransmission of that defective packet. It’s no big deal if a web page rendering is delayed a few milliseconds, but it is an audio disaster. The 75ms latency allows SONOS some slack time to work around small network mishaps. These issues can occur anywhere along the path from a remote server to a thermostat on the local network that suddenly demands service.

SONOS has numerous patents covering the techniques that competing companies must navigate as they attempt to serve multiple clients. Over the years the competition might have specified a maximum of a few units that could be grouped for simultaneous play. SONOS has allowed up to 32 units since inception in 2005. As the competition attempted to increase their number of supported simultaneous clients, they bumped into the SONOS patents.

If the latency is eliminated, overall system reliability will shrink.

TV cable service in my area uses buffering techniques that may be similar to SONOS techniques. Multiple cable boxes tuned to the same channel can drift out of sync over time --- by several seconds! Almost immediately after tuning to the same channel, the audio will be out of sync.

You can have synchronization fun with Sonos too, instead of Grouping a bunch of Rooms have them all individually start playing the same stream and see how quickly they drift out of sync.

Two CD players, each playing a copy of the same disc will usually be out of sync by the end of the first track.