I use hot water for 3 things:
simple precept of chemistry: solubility increases with temperature. Therefore I use hot water to fill my mixing tanks, I want a more consistent solution after I draw concentrates through the hydrominder, result is better mixed HP Soap, HP Wax, PS, FB, Tire Cleaner, etc. Cost to do so is minimal.
I also use hot water for the entire HP Soap cycle, I believe it cleans better, and my customers notice. Note that I turn the temp down in spring/summer/fall, I'd call it more of a warm water wash. In winter I turn the temp up a bit, customers sometimes comment on the water temp & the resulting "steam" in the bays, & how it must cost me a fortune.
When temps get down below 10F I switch from recycled cold water to hot water weep. I've had freeze-ups before, and although it is expensive to weep hot water I choose to not deal with the time & cost of possible freeze-ups.
FYI, it wouldnt be that hard to calculate how much it costs to heat your water; that would help you make a more informed decision. I admit that as prices continue to go up it has occurred to me to calculate it just for a sanity check as to whether I think its really worth it. Havent done it yet though.