Servers aren't typically used for graphics intensive operations on a screen. Plus heat is likely the reason not to put AMD discreet graphics in it. The Quad Core i7 is 10 watts hotter - 45 watts vs 35 watts.
I wasn't talking about adding the GPU to the server machine, but rather offering the Quad Core i7 as an option for the high end mini. Make the price to bump up to the i7 cover the cost of any extra heatsink/fan/psu hardware that is needed to handle the load.