SR is one of the zones which has highest number of trains with PM done by SR. It is one of zones which has highest number of passenger coaches. So, you cannot say "They dont do PMs , they are happy to hand over trains to other zones ."
According to me, SR is the best zone of IR. The Primary maintenance of coaches are very good. If you see the stations under SR, most of the stations are well maintained and neat and clean ones. Good zone with good people there.