The heating is done by a solid state laser diode. It should be very reliable other than adding one more thing to an already complex drive head. (Which undoubted

The heating is done by a solid state laser diode. It should be very reliable other than adding one more thing to an already complex drive head. (Which undoubtedly means the first generation or two will have some kinks to work out, but that's not a fundamental decrease, just engineering). And there shouldn't be much of an impact on durability. The heating is very brief - a nanosecond or so. The idea is not to expand the material physically, it's to increase its magnetic permeability temporarily so that you can write the bit to it and then it becomes stable again.