Wloch28,
Just two tabs are very useful. If you have a rotating vise, all you have to do is either flip the knife or flip the knife vise. I use mine mainly for hand sanding blades and then fine tuning the handle. For blade sanding I slide in a 1-1/2" x 1/4" x 18" steel bar and clamp it all in place. I had the same thoughts when I made mine 6 years ago but decided to practice the kiss princple. With 20 feet of tube you could try alot of variations.
Rudy