Thanks, very informative reply.
I had just read an article saying that Maxwell will be ready for holiday season? But I suppose it doesn't matter due to Broadwell.. Looks like all Mac lines, portable and desktop, will be getting very stale before an update.
I'll probably just wait because I really am just buying this for gaming purposes and a bit of design, so I might as well have the latest and greatest... Well, latest anyway.
Reading around it seems like there is even more frustration with the GPUs in the iMacs than there is on the MBP side, and that's saying something. I wonder if Apple will ever release a Mac that satisfies gamers.
Apple has never tried to sell computers to gamers. Their focus is on professionals and artists, which is why they have always been more focused on CPU performance. Even if they threw in a desktop GPU, game performance would be about 20% worse than on Windows just because of drivers issues. If you really want gaming performance and the usability of OS X at the same time, I would recommend a hackintosh with Windows as your main OS. This assumes it isn't your main machine for any professional work you do though.
If you bootcamp on the 2012 680mx iMac, it still runs AAA titles at high settings and 1440p around 60 fps. That is really solid, but it is not worth $2000 if you are just gaming. I have the 2012 model, and I haven't had any issues with the GPU. I have played Arkham City, Borderlands 2, League, Portal 2, Tomb Raider, Half Life 2, and Crysis 2 all on high settings. It is really solid, but again, if you are just gaming it isn't worth the cost.