Kevin,
For my taste, life is too short to pick up a primer one at a time and place it in a seater. I've always used the Lee Auto Prime. They aren't the best and don't last for ever, but they did what it needed to do, seat a primer and you could feel what you're doing.
I got one of the 21st Century tools when they came out. It has an adjustable cam on the handle where you can adjust how far the seater ram extends beyond the shell holder. Once you play with it a bit, give it some break in time and adjust the handle where the primer seats before the handle hits the body, it seems like it works fine and has a good feel.
I'm sure it will outlast the stock Lee castings, and I doubt the plastic Lee trays would ever wear out, unless you dropped it on the floor. For $75, it's kinda pricey, but life is too short to pick up a primer....one.....at.......a......time.......