I'm convinced that LED lamps are the future, for power efficiency reasons alone. Prices will fall with quantity production. As others have commented, the rapid developments in technology mean that current items are already obsolete,- obviously a problem with maintenance. There appears to be little standardisation of lamp designs yet. I'm sure that would help. As regards domestic use of MR16/GU10 types for retrofit, (which I've dabbled in a little), the main limitation seems to be that they are much more directional than halogens, tending to give pools of brightness and dark areas.