MOTUnation.com

http://forums.macrumors.com/showthread.php?t=1667985

So my 2009 4,1>5,1 Hex 3.33 slightly bests the nMP Quad in the Geekbench Multi-core Performance metric, which is the score relevant for using DP. Cost to build: less than 1/2 of the nMP Quad.

This article/discussion on Logic X and the GPU being integrated referenced in the Macrumors thread.

Some of the posters on Macrumors said that the GPU is after-market upgradeable. If this is true, it makes the whole thing more attractive to me, I would hate to get stuck with aging GPU tech/capability.

BTW, my poor old mac doesn't even make the cut-off point on their comparison list. No wonder my renders take ages!