Is wired Ethernet backhaul worth the trouble?

Yes, where it's feasible. Across the systems we read about, reviewers and TP-Link/Orbi subreddit threads consistently report the largest stability and throughput gains from wiring satellites back to the main router, especially in larger or multi-floor homes. Wireless backhaul on tri-band Wi-Fi 6E/7 systems is acceptable, but Ethernet eliminates the variable.