I did. From what I read, the old can enclosures are built specifically to handle the heat pattern of an incandescent lamp, and don't handle the LED and CFLs heat pattern as well. Supposedly this is also why some people (like myself) had CFLs go bad early in can enclosures, when they were supposed to last for a LOT longer. The units I bought are fully sealed and enclosed and fit into the old edison socket with a pigtail wire. Only took maybe an extra minute per light to install vs. a bulb replacement.
Those CREEs are supposed to be very nice though. I've read a lot of good things about them. Do they have an Xcel rebate running right now on them?