steering may be heavier, but the extra track will benefit you.
i went from 13 by 5 inch +27 offset wheels on my sprinter to 14 by 6 inch +10 offset wheels, and haven't really noticed any downside.
they did tramline when my car was lowered by about 3 inches, but now it has king lows (not very low at all) its not so bad, it doesn't self centre as well as a standard one, but its not really a problem.
might wear out your wheel bearings sooner too, but overall it should be fine and look better too - assuming they will clear your gaurds
just re-read your post, why would you go to a narrower rim?