How about MR16 rather than GU10? I've been following a thread on Greenbuildingforum and they back up my own experience. A GU10 needs a switching circuit to reduce from 230v to 12v which is closer to the voltage requirement of the LED. The general experience is the small circuitry required to control voltage fails a long time before the actual LED. A MR16 offloads the voltage transformation to an external PSU which is better at doing the job and in the worst case can be swapped for a new unit.