I think if I had to assemble a truss-tube every time I used my scope, I would go from observing every chance I get to only 3-4 times a year. So, for me, a truss tube would never do as a primary scope. This kind of sets an upper limit of 10 inches for me.
You don't have to assemble a truss scope to use it. Just because you can disassemble and reassemble a truss scope, it doesn't mean you have to, it just means you can.
Tossing a 16 inch tube scope in your car ain't gonna happen, it's easy with a truss.. Wheeling a 16 inch truss out of the garage out to the backyard, that might take 5 minutes.
Two nights ago, I brought my 12.5 inch truss to town to do some work on it. I took it apart to put in the back of the truck. When I got home, I assembled it to work on it. Then I just carried it out back like I would a tube scope..
Of course the effort required to setup a truss can be overblown, some scopes are easier than others. I take my 13.1 inch apart because it's so easy.. I once timed myself.. Scope in parts in the scope room to scope assembled in the backyard.. Less time than 3 minutes.
I do enjoy large aperture scopes and being retired and living where I do, I get to use them a lot.. Larger scopes are more effort but there's a reward that comes from having made that effort..