The worst I can thing of is extra noise from the heat build up from the sensor being energized for extended period. This is one of the many reasons that image stacking is so advantageous. Cold winter nights imaging Orion is probably not going to notice it nearly as much as those hot summer nights trying to image Milky Way. (I'm hoping to take my camera cooler out for a spin this summer. Just a modified pelican case with insulation and ice chest freezer packs. lo-tech)