I looked one over pretty good. As far as I can tell [both from reading about it then seeing how that compared up close] it is designed around a real commercial need [i.e. getting 48" of cutting through a 36" gate], but for farm use where you want something built as tough as possible for the same money, I'm thinking the M48 is more appropriate. Since you used a ZF48, I doubt you need to put the money toward the ZWing's special characteristics. I didn't ask for a test drive; out of pure curiousity I wish I had.
It may have been the same gage steal and the wings just made it deceiving, but I just didn't find the deck as beefy. Of course the whole machine is [or sure looks] narrower, maybe that was mostly saved in the wheel size [which around the farm, bigger is often better too] but I think they narrowed the frame too.
Anyway, I don't know about the White motors [probably more compact] but I thought several other commerical machines had them [sure can't remember which though.....]. I'm betting you'd get the "commericial hours" out of the drive train just fine, but being almost the same dollar, the M48 seems more appropriate for the challanges I'm guessing vex you the most.
Also, considering you've had a bad experience, tried and true may have it's merits over latest and greatest too.
Good Luck.....and take lot's of action pictures when you decide! /forums/images/graemlins/smile.gif