When I built my bench in 2012, I decided to go with a leg vise for a couple of reasons. First, it was something I could do with parts I could go buy that day. Second, it looked simple to assemble. And finally, I'd learned to hate standard metal face vises while dealing with an old one I'd been using. (That turned out to be more an issue with how I was using it than with the vise, by the way.)
I didn't like the idea of having to bend over to move a pin around as is standard, and I also didn't want to cut a mortise through three and a half inches of very dry Douglas fir. So I came up with a mechanism that would let me adjust it by lifting a piece of wood with my foot while I tightened or loosened the chop. It worked quite well up until a few months ago, when the wooden bar started wearing away from the constant pressure. Looking at it, I think I have two decent options.
1) Upgrade what I have. The aluminum bar (See the last photo in this post for some information about it) is fine, and the only real problem is the pine 1x2 that's wearing away. I could replace it with something harder, and it would be fine. Maple, maybe, or more aluminum bar. It's an easy option, and I know it would work. But the system has some shortcomings, and I've started thinking about alternatives.
2) Move to a cross-based mechanism. For some unknown reason it's usually called a St. Peter's cross, despite actually looking like a St. Andrew's cross. I like the way they work, when they do, and I appreciate the design involved. The problem is the mortises I'd need to cut. The chop on my bench is made of pine, and is pretty weak as it is: I routinely bend it trying to get a good grip on something. So routing out a big strip along the vertical center will leave it pretty weakened. I can replace the chop, of course, but it's an annoyance. It occurred to me, though, that it may not actually need that big a slot. A narrow (1/4" or so) slot a half inch deep would do to allow a piece of steel bar to slide without slipping sideways, and a piece of 1/4" steel rod through it would spread the load out significantly. So I might need to give this a try, as soon as I can figure out how to cut a stopped groove that long in the bench leg and chop.