Stupid questions regarding CUDA, OpenCL and Premiere 6

So I'm thinking of buying something like this.

http://www.gumtree.com/p/for-sale/34ghz-quad-core-i7-27inch-imac-like-new-c...

nice price, nice heft, nice little motor altogether, I know lots of editors going for stuff like this. It'll drive AE very nice too what with the i7 hyperthreading and all that.

I'm also after springing for CS6.

My problem is how my new likely primary editing system is going to perform on this machine, because I'm beginning to worry that its going to perform very badly.

Shane Ross just worked with it and he found, on something non-cuda (90%+ of all current in operation mac hardware) it performs very badly as an editing system. to quote him:

This was…OK on my laptop and the work computer, but only OK. Because neither had a graphics card to enable CUDA and let the Freddie Mercury Engine loose on my footage. So scanning the footage was stuttery, playing back was as well.

Stuttery playback reads as unusable for me.

Lawrence says that he loves this baby, and personally, as someone spending half their day in AE, I figure you know, this is the editor for me, but if the only option in terms of hardware is a tower?? where you can swap the GPU out, then this isn't really going to work is it?

If we're all outputting to monitors at half or quarter resolution because non cuda systems can't support playback of the open timeline at broadcast resolution, and there is no DI codec, then how does this work?

Am I missing something? Also Dennis from Adobe completely hypothetically suggested that it was reasonably-ish doable to point the adobe Open CL implementation to a card not specifically listed by adobe as compatible, does anyone have a view to that?

This is the one component of the Adobe house that needs to be able to reliably throw around a few layers of 1080p with 3 way CC and dissolves on more or less current hardware, without dropping a frame - at the chosen broadcast resolution.

If i can't even properly scrub avchd footage without an nvidia card, isn't this kind of a non-starter right now? until they broaden the OpenCL spec?

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promo producer/editor.grading/motion graphics