I know I've seen 2 of these units in operation at a dental practice and a doctor's office for a couple years.
I'll ask how they are working out and what maintenance they have needed, it's been bugging me where I'd seen these before.
Maintenance items for the 4000 series:
Filter replacement every 6 months ish ($100)
Reaction chamber replacement every 12 months ish ($200)
PPB Sensor Replacement every 18 months ish ($550)
I say "ish" because the way it was explained to me those are the rather "worst case" replacement times, if for example you have a clean room then the filter may last 9 months...
Those are the maintenance costs for the 4000 series units as explained to me by their representative. He said that basically it's a new unit with those new parts, well except for the fan I suppose since it's a moving part however it appears that they use quality components and the filter keeps dust out of the fan.
I am curious how they like their units so please share with me your findings.