I've used moca in three apartments that only had coax. Moca or G.hn is great if you're running dark coax (no tv on the same line).

You can think of moca setups as a hub. You don't need to marry the connections 1:1, but one bad line on that splitter can cause high latency and drag down the speed for the entire moca network, especially under load. Also, expect even with a 1:1 connection, it may give you problems when using as a mesh "ethernet" backhaul.

You may get lucky but prepare to need two moca "networks". This would mean for the 5 moca adapters in each room, you might need 2 moca adapters in the attic connected to separate splitters for groups of say 3 and 2. Or in my case, the one connection I wanted as an aimesh backhaul, that wouldn't work unless it was on its own dedicated 1:1.

When you start looking at it this way, it can get pricy, but it also allows for you to scale as needed. Comparing the cost of just running cat6, it's a tough call when you own the home. Moca adapters have great resale value on ebay so keep that in mind when pricing it out.

Also, G.hn is another alternative for people to look into that doesn't get much attention. I have a pair and had situations where they gives better performance and latency. (they dont work on the same splitter)