I like it!
I have a setup nearly identical with the exception of the wheels...and this is my third one in several years.
Most everything in my little shop is mobile including drill press, welders, horizontal and vertical saws etc. and for sure a rolling vice is NOT as stable as one firmly anchored to a bench top or floor.
But for all other applications, it's design allows me to use it as a third hand, assisting any bench top, drill press or long (cumbersome and heavy) materials during welding, drilling or calculating angles and measurements. I can also use it outside while I paint small (or large) pieces. Two of the four wheels lock and it's not as easy to tip as one might think. One of the nicer features using this design is that it's never in the way, can be rolled outside to pressure was some nasty items...and then put away in the back room until it's needed again.
Here's a picture or two if you're curious..The second picture is a piece of 14' x 1" x 2" ready to be drilled and tapped.
Nice Job on your vise!
Mark