If you happen to have around £2k laying around to buy these mammoth GPU setups with change leftover for PSU to run them, you will certainly have the bragging rights to put anyone in their place. If however you do not have large multiple screens to run and a heavily overclocked CPU to feed them then I fear many will be sniggering behind you back because what four graphics cards can do, the smart money would be spent on a Crossfire/SLI setup which uses just two GPU's and as we have shown today often performs better.
Ay, caramba!! looks like AMD is better for multi GPU scaling and Nvidia for single!!