Dan, there's another drawback for using through-tenons on your benchtop. When you flatten by hand, you'll inevitably run into some end-grain. Not a big deal and I bet many consider it a trade-off for the neat appearance. Just like a wedged tenon, I worry about any tenon that puts stress along the length of the benchtop, given that it's a laminate (after all) and many simply leave voids as mortises during the glue up. My bench is still in my head, so I like working this stuff out, considering all alternatives.