Okay, just tested this. I created a test meeting appointment where I invited a co-worker of mine. He accepted and the meeting showed up in both of our Outlook calendars and on my phone's Calendar.app.
I then went into the appointment via the Calendar.app and tapped on "Edit" in the upper right corner and changed the time to an hour later.
The new meeting time was then correctly reflected on my phone and, after a few seconds, in my Outlook calendar. My co-worker also received the update, accepted it, and could see it correctly in his Outlook calendar.
Looks like it works fine for me.
