I've had a leg vise on the new bench from the get go, while it has worked OK there were some things about it that were livable but my old 1970s Paramo quick release just did them better and easier. I bought a "crisscross" thinking getting rid of the parallel guide and pin would help. After looking at the installation instructions and measuring my chop I had second thoughts about even keeping a leg vise. The crisscross would be a very difficult install with the bench upright, an easier install laying the heavy sucker on its side to do the work, but nah been there done that, ain't going to do it again and the leg vise would still be slow changing from thin stock to wide.
Bottom line several months ago I did a temporary install of the Paramo and worked with it for a couple of months before changing back to the leg vise. Since then I've gone back and forth, install the crisscross and keep the leg vise or do a permanent install of the Paramo. One of the problems with Paramo was where to do the install, on the left side of the leg would put it a little close to the end. On the right side a little too much towards the middle.
I'm not sure what happened but after working on the bench most of the morning I pulled the leg vise off, whacked a big hole in the side of the bench top and did a permanent install of the Paramo. The leg vise sure was pretty and the Paramo is butt ugly on a Roubo style bench but what the hey, it works better. I ended up putting it on the right side of the leg, the photo makes it look like it is in the middle of the bench but the chop closes about halfway across the leg and it is in a pretty good spot. If I had built the bench for the vise the leg would have been maybe 60-70mm closer to the end of the bench top, so the vise is pretty close to optimum position.
There is still some clean up to do and leg vise hardware to remove but it's functional.