Loops and several other 3d moves can be done in normal mode. But you need lots of altitude and very solid nerves. Alot of posts I have read in other forums tell of pilots doing things and then realizing that they hadn't switched into idle-up.

The best thing about idle-up is that it allows access to the negative pitch side of your main rotor blades. That way if your heli ends up upside down you can throw some negative pitch in there and save it.