I'm curious whether or not any of you have started using LED's. I'm especially interested to know how they've been holding up any premature burnouts, performance issues, etc. I attended a seminar given by leading LED researchers about a year ago. They were all in agreement that viable and reliable high intensity LED's were about 2 to 3 years away. Contrary to that, this past year has seen these products (especially MR16 LED's) flood into the market. The biggest concern was with heat. LED's are especially sensitive to heat with lamp life reduced by 50% with a rise in temperature of about 18 degrees F. With incandescent lighting, a great proportion of the heat is radiated out as light energy. With LED's, virtually all of the generated heat is absorbed by the circuit board that holds the LED. For this reason, in most good LED designs large heat sinks are used to dissipate the heat. But when I look at the MR16 LED's I don't see a large heat sink and knowing that most MR16 fixtures are enclosed and many are in hot climates, I have to wonder.