I've known those as recessed lights, or can lights. And yes, heat buildup is a major problem with them. However that is usually only the case when they are in the ceiling and have insulation packed in too close and too tight.

As for growing with them, I can't say. I've never tried it or knew of anyone who did. On hand hand, I'd say they might be useful since alot of the light coming from them seems to be directed at a particular area, instead of going everywhere, and in certain growing situations this could be useful. But on the other hand, they are rather pricey, alot more than just a standard light socket, and again you have the heat buildup issue. Personally, I'd not recommend them to grow with.