I'd look at the deck's overhang past the rear wheels. If the 48" has little or no deck overhang to allow trimming, I'd get the 52". If the 48" has sufficient trimming ability I'd prefer the 48". Because like kawakx125 pointed out it's nearly as fast and will fit more places. Plus it would scalp just a little less, handle a tiny bit easier, dig up the turf just a little less on the turns.
The advantage of standers are speed over having big swath capability.