This type of light
fixture is very common - so common that many people know what you mean when you call them "puck lights" - but comes with many variations. Aside from the likely differences in quality, they also mount differently. When I hear "puck", I think of a very short cylindrical housing which mounts to the surface, usually to the underside of a cabinet (hockey puck proportions, but smaller). Other similarly sized fixtures are intended to be recessed, and may require a certain amount of air space for circulation around them, inside the cavity.
While it sounds like Alan's installation was surface-mounted, which shouldn't have any heat problems, it might just be a matter of the quality of the fixtures' construction, including their venting provisions. I think that good-quality fixtures, properly mounted, should last a long time without getting so hot the bulbs fry quickly.
I want higher efficiency than these incandescent designs offer, so I want to use fluorescents (one installed so far) or maybe LED in some cases, so I haven't put in any of these puck-style halogens - they do look like a good fit for the kitchen area, though.