Looks like a complicated and expensive way to avoid running copper. "Up to 1Gbps" is not confidence inspiring, if you really can't put holes in your walls I'd try a powerline kit first for 1/5th the price
It depends on the topology of your circuits. If you can get both adapters on the same circuit that is ideal, same phase is often okay at reduced speed. Different phases or having other complicated stuff in the way like subpanels is probably what you were dealing with.
MoCa is fine, but if the coax was retrofit replacing it with proper ethernet cable isn't too hard.
What did work pretty well though is MoCa, basically reusing coax/antenna cabling. I get a pretty stable connection roughly equivalent to 2.5G.