It was replaced with an old English metal QR vise, I believe a Paramo but it could be a Record, I had stored in the same tool room. It is a smaller #150 which is not as robust as the #52 but as it is on the secondary bench that shouldn't be a problem. Anyway, it is installed with leather lined wood jaws. I stuck a longish board in outboard of the center and tightened down. Very little racking even with out a spacer and there wasn't any way with a foot of leverage the board would move.
Same song different verse: The leg vise looks "right" on a French style bench and when it is in adjustment works pretty good, not better than an older English metal QR but works OK. The metal vise is no fuss, always works the same, if it racks a little it is easy to take care of with a spacer and is quicker to go from one size object to the next. Pretty and traditional vs. functional, for me not much of a contest. Of course as with all things woodworking and most things life.....YMMV.
BTW, I worked several years on that bench with the leg vise installed. From the get go it worked OK but would occasionally go out of adjustment and become "sticky". A couple of minutes rolling around on the floor in the shavings and saw dust and it would be back to normal and work fine but never better than any other good vise. With no real advantage in holding or speed the leg vise just isn't worth the every month or so up close and personal inspections of my floor maintenance. Of course the dogs might disagree, they figured my being on the floor was play time and an invitation to lick my face.