When they first camee out I went to see them at the ICA show. With 4 EE Tunnels I was looking for the lease maintenance intensive unit. Bought a Viper unit. After a 6 month test at one location I bought 3 more.
After hearing maintenance issues with all the pad type units I am glad this is what I chose. Down side is cost per application due to volume of product used. Runs about 50 cents a car. Pad and now brush type units can run as low as 10 cents a car. Higher volume sales can seemingly reduce product used on the other types of units. Upside is virtualy zero maintenance. Every year or so one of the tapeswitches or a solenoid valve may go bad (Of course a flow jet may die priodicaly). If there is a rainy stretch a nozzle may get clogged. Cost is about $10,000 less than the other types of units, There is no pad replacement cost. So, If you sell 25,000 applications you make the extra cost of the other units back less of course the cost of any pad and brush replacement and operational / maintenance costs for electric and hydraulic drives.
For me, the lack of needed maintenance was the deciding factor. It bumps my top package $2.00 of the $4.00 bump. . Very few sell a la carte for $3.00