Mike,
What is stronger, solid round, or tube?

I think the beauty of the friction system comes when it is designed to let go at a level that protects the components of the vise. And, that can be done, but, it assumes someone won’t put a cheater on the hold down bolts. Having the vise locked, mechanically, might seem like a good idea, until Bubba shows up. For some reason, Bubba has been around most of the used vises I have looked at.

The modern, synthetic greases run far longer than old, white, lithium. The Wilton’s are sealed far better than any other vise I have had a chance to look at, keeping whatever is in the air out of the lead screw. Not sure if your fairly old Wilton example has the rubber seals in it, as the newer Wilton’s do. But, the lead screw stays remarkably free of whatever I happen to be putting in the air and on the bench in the shop on my example. You can make dandy valve grinding compound out of either oil or grease, but, if either is sealed away from the grit right to begin with, you are ahead of the game.

Up your grease game:

https://www.exxonmobil.com/en/aviation/products-and-services/Products/Mobilgrease-28

I like the shelf life and the useful temperature spread on all the Mobile synthetic products.

Probably comes down to personal preference at the point where you are debating merits of two, big, high quality vises. There is more than one way to compress and remove valves from the head of an engine, but, I still use a Blue Point tool that is early 1950s vintage for that task. The old tool works, and, as long as it does, there is no need for me to replace it. Couple people have asked if they could buy it.
But then I’d have to find another.

Let’s see the Wilton when you get it all cleaned up.

Best,
Ted