What recessed lighting technology is recommended for LED?
Get something that works with a standard medium-base floodlight bulb.

But when it comes to safety of heat dissipation and the load on the circuit and switch, don't assume the can will always have an efficient, low-heat LED or CFL. Build so the lighting is still safe to operate with nasty old EZ-Bake Edison bulbs.

IMHO, LEDs and CFLs are both already affordable, since they will pay off relatively quickly in energy savings. I haven't bought an incandescent bulb in years and I'll never go back to them.

One other thing to keep in mind: both LED and CFL bulbs are harder to come by in "dimmable" form, and having non-dimmable bulbs on a dimmer switch, even at full-blast, can result in annoying blinking and buzzing, and the dimmer switches made for LED and CFLs are pretty pricey for now. I recommend just putting in a normal light switch (again, watch that load!) and worry about any dimming features later.