" and a 99.9% uptime guarantee with no scheduled downtime"

That is BS and Google knows it

Why? Because Google can suspend your account at a whim and not even tell you why.

Google did that to a friend of mine, yes, paid account, yes called support line, they basically said "tough, it may return in 48h"

Basically GMail only has the two-step authentication. The uptime is worse than that, the web interface is not that great, it is slow and interoperates poorly with IMAP/Exchange/POP3 access.