I've never owned a two wheel tractor, having looked at BCS and Gravely over the years, I agree that the main benefit of a 2-wheel would be maneuverability.  Am now on my second Wheel Horse garden tractor, having owned each for 20 years.  Am sorta looking about for a new machine but very unfortunate that TORO has discontinued manufacturer of Wheel Horse.:

At this point the Wheel Horse still runs well and mows well.  But that's not going to last forever.  Got a nice buy on a Sears used rear tiller a few years ago for the gardens.