although hot systems are much better (faster) on first cleans, conservatory roof facias and so on, i dont think there is really any difference on regular cleans, so on ballance when you weigh up the extra running cost against the benefits i dont believe it is worth going for hot. and this is why i have decided to keep my business cold for now at least.
however i have considered getting one hot van and making it a dedicated team for first cleans and the above extras and charging more,