CF is good as long as you play finalized (drivers, game updates) AAA titles. For me it didn't handle well some Indie or F2P titles (such as Path of Exile) and Diablo 3 didn't support CF after a while as well.
Well and as long that's true it's nothing for me, I don't want the fiddling involved with it, after I had my fair share of it. Just too many variables, game support, drivers, amount of video ram, power consumption. It's not worth all the hassle if you ask me. But the Radeon Pro Duo mostly isn't a gamer card anyway, it's more directed towards producing stuff, so who cares.