I've had both and can tell you I make more $$$ year round having heated water. In the beginning the boiler didn't work and I only had cold water going to the bays. When I installed the HE HTP Tank Style Heater, it paid for itself in 6 months over the previous years income. People do notice. I heat
soap and wax cycles and have the water heater set on 100°. The nice thing about a modulating/condensing HE design, you can run them at lower temps without it self destructing or adding a mixer. In the winter when its cold, a 100° wand feels pretty darn warm along with the steam it creates. People love it. The HE water heater is so efficient and cheap to operate, I just let it run all summer.
So I guess operators using only cold water, you have to ask yourself, am I leaving $$$ on the table?!