I dunno, he makes a pretty strong argument for Ti. Kinda makes me wish that Feather would offer a AS-D2Ti.
Seriously though: I am perfectly happy with the weight, efficiency, and maneuverability of my SS Vector - it's a fine and innovative razor. The Ti version may well be an improvement for some, but I can't see any real benefit in a Ti upgrade for me as the Vector is already pretty svelte. I suppose the difference between SS and Ti might be more apparent with larger razors but I am not convinced that it makes enough of a difference to pay a 30-40% premium to find out.
I think your logic is sound regarding the Vector Ti. The difference is real, but the relative performance gains are smaller than for the Blackbird because there’s less material to cut. For the Blackbird, going from SS to Ti is transformative. For the Vector, SS to Ti is a meaningful step, but not revelatory.