hi there
i do know a little bit about them, but not really for open debate to be honest.
jani-king and dublcheck work very much the same,
as i understand it there is a guaranteed income level, based on your level of investment, but some of the contracts that they get arent great, ie dont stack up.
so its a bit like any thing, you pay your money and you take your chance, it opens up the whole debate again about, how you want to run your business, and how bug you wnat to be over what time scale, and whether you do it yourself, or use a franchise route.
regards
martin