I've been using this jig for some time now (years). I don't bother with it when I'm doing "quick and dirty" joinery; but when I'm striving for really perfect dovetails, the jig comes out. I like it because it doesn't let the chisel creep past the scribe line. I do my heavy chopping first and sneak up on the line. The last cut is braced against the vertical stop. It places the chisel directly in the scribe line and guarantees a vertical cut. I find that there is less back-and-forth wiggle in the joint if the back of the socket is perfectly vertical and flush with the tail board. Similarly, the little spacer board I use between the bench top and the chisel for paring the ends of the sockets gives me a consistent, square socket end. All of this helps keep the joint square. I hear you about the glue squeeze-out. I use very little glue, just a dab on the sides of each pin socket is all it takes. I don't get much, if any, squeeze-out.