That is an interesting question. I was under the impression that any vehicle's ability to refuel & rearm could be set by the admin, similar to camos and equipment (antennas, deep water kit, etc.). I played around with these vics in the editor in June and I believe they worked with ACE3 mechanics similar to the HEMTTs but I don't recall 100%.
Re: the 1152, I have noticed players dragging them around via tow ropes behind their Humvee or MRAP... not necessarily "abusing" the mechanic per se but since they give unlimited ammo it feels out-of-character.
The beauty of the 1239 is that they can equip CROWS systems, hold 4 passengers, and act as rearm/refuel for frontline armor. No need to pull a dummy Humvee behind you.