Hi,
Just an input from another Office 11 user here.
Been using for about 2 weeks with my new 11' air.
Compatibility is certainly not an issue at all. All sheets, even those with a terrible terrible formattings (hundreds of tabs with bad formattings which lags on my Excel 07).
But personally I do encounter a few drawbacks.
One: Each cell is ridiculously small with normal zoom. But well, this one is easy to get through, just highlight all tabs and change zoom to around 130% will make it looks like normal 13' computer.
Two: Frequent program shut down unexpectedly on certain excel files. This one is pretty annoying. So far it happened to me like 10 times already. I set the autosave to 1 minute to reduce the damage of this issue.
Other than that everything is great, it opens Office 11 with blazing fast speed as well.
For Outlook, still not configured mine yet cause my old Windows Outlook have tremendous data which I'm afraid some sync problem can happen on the transition, will do it when I have a lot of spare time.
I don't do much Word related stuffs daily, so cant comment on that also.