We have more than 40 ceiling mounted recessed lights. Some in a so-called cathedral-ceiling (directly under roof insulation). Should I be concerned about the air leaks of old cans? I'm 60 miles north of New York City - it's 19 deg F now and won't get a lot better until end of March so heating costs are a concern.

If I do replace these, I could use either "air-tight" or EneryStar-rated cans (both IC-rated). Other than the double price of EnergyStar-rated cans, I don't see what could be different than than being air-tight. Am I missing something?