From an Army guy I work with and a crew that flew one into CWF that I got to talk to: apparently, the initial purchases did not include air conditioning (had to keep the per unit cost down) and a couple of other things (can't recall what) that pilots would consider required but bureaucrats would consider optional. The result is that they haven't been used much in their intended roles (personnel transport, etc) and the units that got the initial batches have not been too happy to give up their 60's.