I have a pair of 4" rear spacers on the rear of my 3720. It put my rears out far enough that a 72" rotary cutter extended a mere 6" on either side of the rears. But doing so ended up putting my front wheel footprint inside that of the rears. Results; two sets of tracks (four total) on soft ground/snow. Plus the forward view became an inaccurate gauge of how far to stay away from fences/treelines/etc when mowing. So I added a pair of 2.5" spacers to the front. That squared up my front/rear footprint, gave me a forward sight line for the rear mounted mower, and set the outside edges of the front tires to the same width as the 60" front bucket..
Bottom line, the center pivot design relative to stability held no influence over my decision to add front spacers. Given the other benefits already described, I felt it money well spent
//greg//