Dynamic:
jnimmo: ...it is really nice not having to backup Exchange...
Think very carefully about that statement. If you accidentally corrupt, or someone maliciously damages an email or a folder in your hosted Exchange mailbox (be it Office 365, Intermedia, or other), what are your recovery options?
If you accidentally delete (or something causes emails or a folder to be accidentally deleted) and you don't notice for a month, what are your recovery options?
Yes apologies, good point - obviously depends on requirements, retention policies etc.
Another option OP is I think O365 from E3 upwards gives you the on premise rights too, so you could use Sharepoint hosted and Exchange on premise or hybrid if required..