The average latency for MoCA 2 devices is 3.5ms which is half what you say the "minimum latency" is. The latency on my WiFi averages 7ms. So it's likely going to be better than a WiFi connection.

My MoCA devices don't use crazy amounts of electricity either.

It could also depend on where you are. In the US, homes often have quite good coax wiring. That might not be the case in many parts of the world.

> I'd much prefer a consistent <1ms latency 10 Mbit connection than 10ish ms gigabit with 100ms spikes when next door boils their kettle, etc.

Honestly, this just feels like FUD. You've made up a scenario with latency numbers that are wrong claiming with zero support or evidence that a neighbor boiling their kettle will make a connection bad. It sounds like you briefly looked at MoCA, never tried it, but formed a very strong opinion about it based on basically nothing.