Mostly a matter of iCloud service reliability and the effect that may have on client choice.
To clarify: I have attempted to use Outlook on iOS with an Exchange/EAS account. Office 365 through an organization. Read status does not synchronize in the background. Messages read via webmail continue to show as unread on the client. @campyguy, when did you say this was hopefully going to be straightened out for sure, roughly? Outlook.com during migration, I could understand...
To clarify: I have attempted to use Outlook on iOS with an Exchange/EAS account. Office 365 through an organization. Read status does not synchronize in the background. Messages read via webmail continue to show as unread on the client. @campyguy, when did you say this was hopefully going to be straightened out for sure, roughly? Outlook.com during migration, I could understand...