'Unfortunately' a few years ago I did about 500 hours instructing in them. There was no night restriction on the DA20 but it was VFR only.
Performance and fuel burn were certainly much better than a C152 however if you're going to be in one for more than an hour you really need the facility to be able to stand up and allow blood circulation to return to your rear and legs. Also on a hot day it is simply a flying greenhouse.