Jim,
There is a point at which you are no longer in the realm of small vise work. It happens to any guy the first day that he installs a vise in his shop. I recently rebuilt a Stahl folder at work, and pressed 18 bearings out of the boxings with my vise. I had access to a small press, but, the Wilton is the better tool for the task, because the bar is keyed, it was rigidly mounted, and was at the correct height. The key holds lateral movement of the movable jaw to less than .005. The Reeds, Parkers and any other square bar vises will not have that feature. That means you will stop, open, reposition, and constantly check and recheck to see that your push remains square to the work. They are also old, and likely to be sloppy, at this point in time. The old vises were blacksmith vises, to a large degree, but, the Wiltons have far more precision built into the task of moving the jaw in and out. You can do precision work on the Wiltons that is tough, or impossible on an older vise with some wear, and, you can do blacksmith work if need be.
Ive owned both. The Wilton makes most tasks simple. It is also difficult to find older vises that dont have a bunch of lash from wear and abuse. I dont want to turn the handle 3/4 of a turn in or out before I get a reaction on the movable jaw. That makes it too hard to position the work. I have cut new nuts for old vises with buttress threads, and while it improves things, it is not like a new Wilton.
The guys that restore and collect vises have their own reasons for doing that. It may not be to have the best all round tool up to any task that comes your way. Nostalgia doesnt pay the bills. The sports car and tow truck analogy is way off track, by the way. The bigger vise has more material on the jaw surface, spreading it out over a larger area, and using less force to hold the work than a smaller vise does. The bigger vise gives you options the smaller one cant. The big vise can do big tasks, and is useful for detail work as well. The little vise is useful for detail work, and not up to bigger tasks. It isnt an accident that you dont see any Versa vises in those gunmaker videos. I cant argue with Jacks assessment that 4 is minimum, either. But, Id say not a Sears Craftsman 4, and if I have to explain the difference between consumer and industrial 4 vises, I might as well be at the beach.

Looks like our homeboy jOe be a Lowes kinda playa. We should have known.

If you want one vise in your shop, you would be hard pressed to beat a round bar Wilton. I like the 500, because it does not have the external cuts on either jaw like the 600 and 800 models, has a 5 jaw, has adequate mass, and is smooth on top. Is is built of ductile iron, keyed, sealed, lubed, and has a functioning company supporting warranty and parts supply. The best time to buy one was 20-30 years past, the second best time is right now, before the next price increase.
What is not to like?

Best,
Ted