I will not use Manchester if my flight involves departing from Terminal 3. Too many bad experiences.
I would be back to using Manchester again if BA moved to Terminal 2.
On another note, a friend of mine missed his Jet2 flight to Barcelona from Terminal 1 this morning. He checked in on time and dropped his baggage off which was tagged and accepted. Then he went to security and it took so long to get through he missed his flight!