The handling of 3.5 on both front and rear is acceptable but not fantastic.
Handling best with 3.25 front 3.50 rear.
In theory. In practice, there's no noticable difference, at least with standard handlebars.
Now that I put clip-ons on the bike, the steering is feeling a little slower; of course, there's less leverage from the narrow bars, but maybe the fatter tire is also showing its influence.
But all in all, from 3.25 to 3.5 is an eighth of an inch on either side. Yes, the carcass is a bit bulkier overall, but it's really not a dramatic difference. Even on a 30-lb mountain bicycle, a quarter-inch difference in the tire is only the bare minimum you'd need to notice any change in handling.