Hi. I'm looking after then QA approach for an app vendor. The internal testing is pretty robust but because they operate in mobile there's the thorny problem of devices, platforms, languages mobile coverage, accessibility etc. In other words the permutations of variables is pretty huge. So I'm thinking of trying to establish a relationship with a crowd testing outfit. Do any of you guys have any experience of any such outfits either from the perspective of having been a client of one or working for one?