Recessed lighting - Energy Conservation or Waste?

I've been in so many homes lately that have a number recessed lights in various locations.
As recessed lights do not protrude down from the ceiling, they are very popular.
However, many recessed lights are holes in the ceiling where heated air goes.
According to Mr. Handyman, recessed lights come in two designations:
IC - Insulation Contact and AT - Air Tight
Insulation Contact means the exterior surface of the can in the attic remains cool enough that insulation can come into direct contact with it without fear of it being a fire hazard.
Air Tight means there is no air circulation from the room into the attic.
The issue with non IC cans is pretty obvious. If you can't put insulation near the cans, that part of your ceiling is less insulated.
The issue of non AT cans is not so obvious to most people. A recessed light is installed in a hole cut in the ceiling. You then install a heat source (the light) just above the hole. As the light heats the air around it, that air rises. It rises through openings in the can and helps heat the attic. This leaves a slight negative pressure in the can itself. That in turn causes cooler air from the room to rise into the can. That air in turn is warmed by the bulb and the process/cycle continues. This is called "the stack effect" and is in fact how chimney's work. So, when you install a non AT recessed light, you've installed a continuous "heat leak" in your ceiling.
For the past few months my source, Mr. Handyman, looked for an inexpensive solution to this issue with no success. Every solution he found was more expensive than just replacing the entire recessed can with an AT can. Then someone at HomeZ (a company that provides home energy and water reduction services) gave him the answer.
You can now buy an (almost completely) air tight recessed can trim piece. They are easily installed in 10 minutes or less.
There are two different models that are available. Halo has an air tight trim piece that is available from Amazon.com for $13.43, and a less expensive, and perhaps not quite as good trim piece is available from etoplighting.com for $6.50.
So, if you've got non AT recessed light fixtures, including the addition of these air tight trim pieces may be the most important part of your home weatherization project.