Bushing dies work best when combined with neck turning. The bushing will size the outside of the neck to the specifed diameter and if you have varying neck thickness, the variations will be pushed to the inside to bear against the bullet. That is, of course, if you have removed the expander and stem from the bushing die. If you don't remove the expander you might as well be sizing with a FL die, it would be a lot cheaper.
If you neck turn to a consistant neck thickness and then size with the bushing only, then you can pre-determine your neck clearance in a custom chamber and the bullet grip. You can buy the appropriate bushing depending upon the neck thickness you outside nect turn to. With the Lee Collet you have to determine the thickness of the neck brass you need to give the bullet grip and clearance you want and then turn to that specific thickness.
In a factory chamber without a tight neck and with no neck turning then the Lee Collet will do just as good a job as the bushing dies with less hassle at 1/4th the cost.