I thought about this last night. I priced a new double vise in a few places. I buy mid quality vises. My products are perfectly fine with that repeatability and accuracy. I could buy an identical vise to what I have cheaper. It's a nice little vise from Shars. 4" size. I like it a lot and use Monster jaws in it. I am working on using a third jaw in between two parts. Not sure if I will need to mill a key to bolt under the center jaw to keep it semi in place. Now my jaws do not lift with only two, but the test will be to see if the third center jaw lifts when two raw parts are clamped down. Won't cost anything but half a set of jaws to find out.
That will give me two parts per tool change routine rather than one. It should save some time.