All these things work, the real question with a portrait is, what do you want?
For backlighting examples you might look at Jose Villa's work. Just google for his sites and blog. The majority of his stuff is backlit and sans reflector too.
When you use any type of artificial light in the situations you describe you are essentially going to set the camera exposure to place the background where you want it then adjust your reflector (or strobe) to place the subject brightness where you want it in that scene.
By changing the shape of the reflector, the distance to the subject, and using "feathering" you can adjust quite nicely. An incident meter and a stand or assistant will help immensely.