I love it! That's kind of what I did for a while. Only I ran 4ft long F clamps across the top of my table, because there isn't a lip underneath.
I decided to build a "proper" Moxon vise mainly due to the fact that I'm 6'2", have short arms, a bad back, and a 34" tall bench. So my Moxon gets my work up above the table by another 8", making it easier to see and saw. I love the low table height for planing. And for mortising and chisel work, I have a chair/stool thingy I made to work from at the appropriate height. But sawing dovetails was just no fun.
Also, it doubles as a bench slave. I can stand it up on end and clamp a spare board in it to support the other end of a long board in my leg vise.