I own both the DFGT (played GT5 for over a year with one) and the G27 (bought last January. If money is no object, get the high end Fanatec or Thrustmaster wheels. Make sure in any case, you have something very stable to mount it to and if possible, bolt it down. The DFGT was a waste of money. The G27 + a wheelstand pro deluxe ran me a bit over $300 when purchased. You can tell the difference in the two with no power applied, and once you plug them in the gap becomes even larger.
Someone said in this thread that Logitech may be producing a new wheel. Strange, last I heard they were bailing on the wheel market. Do you have any references to support that claim?