We are currently in hybrid mode between 2007 and 2013 because we have some old code that uses MAPI (i believe outlook express or something) to check mail for 3 mailboxes.
When we first were going to deploy Exch13 MAPI wasn't supported, so this was our plan.
I read somewhere recently though that they added MAPI over http support for Exch13 in an update. Is this the same or something different?