I don't have one of these systems, but people I know who have used them in the UK were not that thrilled with them, the main problems being:
-The ones sold here are small, so if you have more than one dog or even one LARGE dog they do not cope with the volume.
-The chemicals they sell are expensive, unless you can find another, cheaper, source.
-They can 'hum' a bit in the summer months.
I'm sure it would be possible (and cheaper) to build your own industrial size one.... Persoanlly, I just scoop and throw it in the bin.