I bought Varios from a fellow tosser, and bought the BMW bags to go in them from another. I have a big Givi topbox that lives on the bike.
I only fit the Varios when I need them, like I’m travelling. My wife & I use one bag each, and stuff like shoes goes in the topbox along with tools etc. I think the Varios would be a pain without the bags, though of course, you’d get more in them. Personally, I’d prefer them to not be variable, the mechanism itself takes up yet more space, and I don’t see the need for them to be narrow, I just take them off.
Where they really win is the attachment to the bike which is simplicity itself, takes seconds, and the bike looks “clean” without them, no scaffolding. I’m surprised Givi hasn’t come up with a similar solution.