The only real difference I see with your jig and the moretraditional approach of glueing is that you are applying more pressure to the edges of your laminates. The wooden blocks you are placing across the laminates are bound to flex a little since the "clamps" or bolts are tightened in unsupported areas. This is however splitting hairs, hairs that may not matter, I really dont see any advantage to your method of clamping, over the alternative of just laying a board across the top, and one across the bottom and the using them as clamping cauls. If I was worried about getting equal pressure across ,my glueups, and I am, then using harder wood than the pine you use is the way to go. I use either very thick and quality plywood or oak/maple. It will flex less and act more as an extension of the clamps than a softer piece of wood that will more likely put more pressure directly under the clamps than in the spaces between them.