any body actually TRIED it and not died ,(have a set of mavic cxp22,s and some old disc hubs)if so how was it did tyres roll off,did feel crap?

According to the ETRTO, it’s probably ok if the inner rim width is 17mm or above. As for how it feels, that depends on how hard you are pushing the tyres, what pressure you have them at, etc. It’ll be fine for canal paths, but probably will be awful on a DH run. Where your usage and tolerance for tyre feel fit in there is entirely up to you.

I ran some 2.1″ 29er tyres on some Open Pros within living memory. Note LIVING memory. I did not die. Just makes a very round tyre profile.

My Gryphon is more than happy running Bonty XR3’s (2.1) on Mavic A719 rims. It works / rides fine (on that bike at least) an’ when it comes to tyre replacement time, it’ll be getting the same again.

I like the A719 rims, but at 19mm, they might not quite fit with what you think of as a road rim – I think they are regarded by Mavic as ‘touring’ rims – they are certainly tough enough.