Vacs
I believed that combo vacs would increase revenue, so I replaced my older vacs with a shampoo/vac and a fragrance/vac. Ditto with including bill acceptors.
What I experienced was disappointment. People rarely used the bill acceptors because few knew they existed. (My vacs are on the ground, not on a pedestal, so it was hard to see or find the bill acceptor down so low.)
And, I can say without hesitation that the extra money for the shampoo option and fragrance option never came close to being made up for in revenue-- and I'm talking gross, not net. The shampoo head was damaged and needed to be replaced at a cost of over $200, and I seriously doubt that the shampoo function even grosses that in a full year. You can't tell as there is no reporting of income from vac versus combo function.
My vacuums are hidden from view when you enter the wash, so many people wash and drive away-- leaving my vacs unused. So, in my case, combo vacs were *not* worth the extra cost. I have since replaced both former combo units with standard 3-motor turbo vacs, and I have less maintenance and feel this is right for my location.
If your vacuums are prominently located and your vac revenue is a good percentage of overall gross, the combos are probably a good choice. In my location and market, they were not.
fyi I thought I had dixmor timers in my JE Adams units as well; however, I believe they are actually IDX?