I'm sure compared to the severe bump steer of a stock trucks system, the minor C-channel flexing you might experience with the Vega style cross-steering system would hardly be noticeable, and the entire thing would probably feel like an enormous improvement. If it improves the handling on a Model A, with a much lighter frame, I'm sure it would on a truck too.
I would personally like to do a rack and pinion on my truck, but if I do, I will make a custom support for it and not try to attach it to the front axle. And being a rear-steer system, I doubt if you would even notice it behind the stock solid front axle.
