> single 9 of reliability
Out of curiosity, do you actually use it 24/7? The world doesn't collapse every time o365 goes down... (which is also pretty often)
if it's judged only by the time it is expected to be in use (work hours), reliability is likely even worse than the 24/7 measure.
In my experience the downtime tends to coincide with peak PT timezones. If you're in PT, it's very inconvienent.