The goal is to exclu visites done by our dev/quality team. They pollute the data. I can't use exlues IP because they use proxies or smartphone.
I think that using userId is best to exclu our dev/quality team.
I'm wondering why you simply don't insert the tracking code for those users?
Nevertheless, this is not a feature we will implement in core. But it should be quite easy to implement as a custom plugin using the event
Tracker.isExcludedVisit. You can have a look at my plugin to see how it works.