If you know what G-sync is, you’re not the target for playing games on the Mac. I don’t believe the Mac will ever be targeted at the serious PC gaming market. It’s targeted at people who play consoles and would like to play a few games on their Mac.
I love the serious gamers who try to make it work as a challenge. It’s the equivalent of driving screws with a hammer. Sure you can do it but you have to ask yourself, why are you doing it? If you’re doing it because there’s a select few games you like on the Mac then it makes sense. If you’re doing it just to be different then it really doesn’t make sense.