Depends on what you're buying. I'd run a mild steel on the street, and as long as you have everything bolted down tight and adjustable A-arms adjusted to where they're supposed to be, nothing should change about your steering except there's less weight on top of the wheels so it'd be easier to turn the wheel.
Chromoly on the street = broken.
As far as sponsors, I'm not sure who I'd personally go with. Folks that have them, post up your opinions!