ROAR = Fabulous which is a domain holding page system for domain owners. I’ve had tremendous results over the years with them and I must say Dan is one hell of a personality!!
Don’t forget that there is a relationship between some of the higher value gambling domains and the ROAR owners though. It didn’t put me off but may sway your view.
The ROI is there but NOT at the same level as search engine PPC.
Again, this is simply my 2c and your mileage may vary or differ