Well that would still let you get another 7970 when the price drops so you'll get the crazy bling for longer. Honestly the price of CF capable boards, especially the AMD ones are so damned cheap if you want to game you are probably better off with a CF board, they can usually hold more RAM and have better options for tweaking anyway.
Being a PC fixit shop guy in a poor state and having a couple of teens that game I just can't go batshit on the cards, as any card i get for myself I'll end up having to get the boys something equal to it so we can game together so if its one thing I've learned its how to stretch out that bang for the buck and get the most for the money. that is why me and the oldest are running Thuban Hexacores and the youngest an AMD quad, by going with the AMD chips I was able to build 3 pretty damned nice PCs for less than a grand, and that is why I'll end up getting the HD7750s to replace the HD4850s we are running now as 3 of those this fall will cost less than your single card.
But if it were me I'd still stick with the x7xx and x8xx simply because with CF you can buy one card now and in six months buy another when the price is cheaper. With the x9xx cards they really don't sell those in mass quantities so the price never drops nearly as far,whereas with x7xx and x8xx you can get some crazy cheap prices if you watch out.
As far as VRAM...you ever thought about a caching SSD? i have a gaming customer running a Sandisk caching SSD and he just raves about how fast game levels and textures load, with that caching SSD working as a buffer between your HDD and your RAM/VRAM you can seriously cut down the time it takes to feed that beast of yours, but of course with you running ultra HD I'm sure nothing is gonna top insane amounts of VRAM, still if you have already bought the monster card nothing wrong with having the option to CF it down the line. It'll let you squeeze more bang for the buck without having to keep buying the insane-o priced cards constantly.