I have an M5-3C-120W that physically controls three lamps. I use an M5-3C-86W (no loads on the three L lines) to remotely control, via automatic scenes, the three L lines of the M5-3C-120W.
The latency time is very long (even 3 seconds). Other automations also show long latency times, but all in the last month. I have more than 40 Sonoff devices. I also can’t update the firmware of the M5-3C-86W (currently it’s 1.0.0)