Are these separate tickets or on one?
If a single ticket, I'd go for it. If you miss the connection, it's their fault. 75 minutes in MAN is no problem and they normally know who is connected between flights.
If it's separate tickets you may have a whole host of problems with bags and check-in, if you can't check in online. Plus, if your connecting flight is delayed, you'll be dumped with little recourse.