Though I've switched to the Redding S-Bushing Neck die, I used the Lee Collet Neck Sizer for several years. They work well, and if you need precision control of the neck sizing process, Lee can make a specific sized mandrel for you. Personally, I find changing the bushings in the Redding to be a bit easier than dealing with changing mandrels.
The main complaint I had with the Lee die, and it was my fault really, is that sometimes the collet can get "stuck" without you noticing. Invariably, when I noticed it was after I'd already seated bullets in a hundred cases and the bullets would still "spin" in the necks. Paying attention is the key here, but loading 600-800 pdog rounds can become a mind-numbing affair. /ubbthreads/images/graemlins/wink.gif
Though I do prefer the Redding die, the Lee die is good, and a great value for the money.
Mike