This is a lo-o-o-ong thread and I haven't followed every word of it. Is it fair to say that out of flat and out of square are two different measurements? Also I can add that I have a very nice commercial shooting board made entirely of baltic birch ply-wood; with a ramp, and an adjustable fence. I sometimes go weeks or even months without using it. Most of the time, I find it very out-of-square after that time interval. I guess my point it that a plane or a shooting board have to be judiciously set up to get good results. There is no guarantee that both will be ready to use off the shelf.