Vises can be quite personal. Some folks cannot believe anyone gets by without a leg vise. Others favor the shoulder vise. Some have to have QR features or feel handicapped. Vises just seem to be one of the things that don't have a "best" answer that fits everyone.
My vise nemesis was racking. I made a stack of 1/8" "cards" on a dowel to use as a variable spacer for my old QR vises and it worked great as a solution but, it was a solution to a problem I fundamentally didn't want in the first place. A twin screw rig was my nirvana; others may not really care.
The cool thing about the twin screw is that you can do this too.
Don't be confused; in this pic the new bench top is setting on my old bench. It was just a pic to show someone what I was doing. There is no racking problem as the screws support each other.
Hope this helps with your decision. I think your question has helped me decide to just get on with mounting the small twin screw at the tail ;-) Thanks!