I run scag 36" walkbehinds, you shouldn't need to mulch or bag, if want to go ahead and I'm sure someone will argue. here's the deal I run Scag high lift blades, OK that's what blades I use.
now for why you shouldn't need to bag or mulch. the walkbehind will have more blades, higher blade speed, much larger discharge opening and deeper deck, all equaling more efficient days for you mowing.