Hi BFedRec,
Unfortunately, the Reflex demo that can be downloaded has limitations, for obvious reasons. There's no way of controlling the demo with a (analog, digital, or USB) joystick. I tried them all .
But, you can still use the mouse to control two of the channels.
This is what I do: First initiate a flight. Then press F8 to bring up the "Channel Display" control window. Then move any two sliders to control the plane/heli.

NOTE THAT ONLY THE FIRST TWO SLIDERS YOU MOVE WILL BE USABLE

Yes, I bought Reflex. It's like $155 or something like that. And after been flying RealFlight G2 for 3 days now I can say that Reflex is somewhat more realistic in terms of the physics of the flying model and ground physics too. Mmm, I guess I need to put some heavy winds/gusts in G2 to make it more real because with no wind the planes are too easy to fly. But, wooo, G2 looks soooo nice....

So for me, the perfect sim will have RFG2's looks with Reflex's physics.

Have fun