@baptiste2k8,
Some time ago there was a request for info (see here) about testing, by the creator of Node-RED. As you can see, there was also not an overwhelming amount of feedback, mostly from hobbyists. And it is all about testing flows, not about large iot solutions.
I have send a mail to a former collegue of mine, whether he can answer your survey. He has worked as a profession with a large enterprise iot solution, and with expensive consultants 
Hopefully he can provide you some feedback...
