A house down the road has a bunch of landscape lighting that uses Sylvania MR16 LED bulbs. They are installed in completely sealed, waterproof fixtures. Tha packaging on the bulbs states clearly “Not for use in sealed fixtures.” The bulbs draw around 6-8 watts, are rather small, and get to about 85C in open air. No telling how long they will last in those sealed fixtures.
My G4 hologen replacements: Hera halogen counter light Nichia 219 retrofit