I have the older style (not the $400 one) and we only use it in Winter - bloody excellent though! However, we try where possible to pre-heat any water on the fire ... might as well save some gas for when we do need it and the fires going anyway so it's smart. It's like having a real shower ... only you are camping.
We also turn it on and off (best part of the AquaCube ... shower head operates the on / off ... no need for a second person) and soap up to conserve water.
During Summer, Spring, Autumn, fill a billy and put it on the fire ... pour into a bucket with cold water to suitable temp ... use a cup to move water from bucket to body ... TA DA ...
Kit_e