The only caveat is you cannot have two MoCa networks (fios and your router) you would have to rely on the fios router for your network (unless you are very very network savy)
Have used moca with excellent success over the years! Just make sure all your splitters are moca certified and you put a moca filter on the line coming in if it's cable!
The Bitterness of Poor Quality is Remembered Long after the Sweetness of Price is Forgotten! - Benjamin Franklin