Well, after a few hours work the first dedicated chair makers bench in Sumner county is complete. First and foremost I think any bench should be massive, heavy, thick, and won't dance across the shop in use. The Roubo style fits that bill perfectly. But beyond that a chair makers bench should be slightly wider (26 1/2'') to handle the rake and splay of the legs. Not too wide since carving a seat involves 180 degrees of movement around the seat while carving. That is why the top is shorter (4') in length.
Matthew O'Neill also gave me a good tip the other day of using a center punch on the shaft of the hold fast to help grip the hole. Good stuff.