While reading this thread I've been thinking about why would someone need to go through such precision to attach the plate. Why not hold one plate to the other and mark the holes with pencil? I've come up with two answers, please respond if you know of others I'm missing. 1) keeping it centered on the router allows one to use the edge of the router plate as a guide because the bit is equidistant from any place on the edge of the plate. 2) OCD
I haven't used the edge of the plate as a guide in years since I built a router table with fence. Occasionally I'll use bearings and guide bushings... Oh I just realized that if the perimeter of the plate is off, so is the bushing.
Are there other reasons?
Mike you were using the centering jig in the table plate, is there a reason there or just because you had the tool already?