I agree about the linear bearings. My Dewalt 708, that I bought in 2006, if I'm remembering correctly, still cuts dead true. It's never been locked up though, except one time when someone else was using it. Other than that one time, I'm the only person that has/will use it. He was push cutting. I never do.
Also, I keep two Radial Arm saws. One only for precise 90 degree crosscuts, and one for rough work, and cutting dadoes. The one for precise cuts has never been locked up in wood, because I'm the only one using it.
I would guess that locking one up would be as harmful to one as rough moving.