Custom transform orientation and animation

In GMAX/3DS Max it is very easy to change the pivot point of an animated object, such as a flap. The flap often has its local orientation in multiple angles.

Blender is very different... After reading the forum I understand that the suggested method in Blender, is to create a dummy object to align the Gizmo.
However, I made a custom transform orientation, aligning the gizmo along the axis of two vertices with CTRL-ALT+Spacebar (Create orientation in Edit Mode).

My flaps exported fine and shows correctly both in MCX an Prepar3D.
Is this an "unsafe" method in Blender? (I have just started out with Blender 2.79b, and are doing some tests)