My angle:
My Adderall generic and Brand-name affect me differently. My old doc understood there had been many of his patients (me being one) that reported it and we were able to talk about it with open minds. A fellow technician also has noticed a difference. Like the Name Brand is more potent. The crashes aren't as bad as with the generic. And heck, they even taste different. The generic is sweeter and the name brand is bitter... well for what it worth anyway. Hey, a difference is a difference.
My opinion:
If you feel a difference, your doc needs to listen to you when you say there's a difference. I had time finding a doc that would listen to me. I finally found one and then had to move away

I'm starting to look again and not enjoying it.
My punch line:
If you doc is listening to his knowledge, his expieriences and his logical reasoning... his priorities are amiss. The focus doesn't need to be on his abilities as a doc but your needs as a patient. He needs to listen to you like he's solving a mystery.
My supporting statement on listening:
I'm a network engineer. If a user says her PC flashes a message and reboots before she can read it, and there's nothing in the event log saying this ever happened, then I don't use my knowledge of PC's, my past expierience with "job securing users", or logically say it's not happening because the logs say it isn't. I listen and most of the time, it's an interpretation issue. After talking with her, probing her for more info I realized (here you'll realize the importance of someone with a great affect on your livelyhood listening to you) that it most of the time happened when she got back from break. The "message" was a screen flikckering coming off the blank screen screen saver and not a message and the reboot wasn't a reboot but the whole scenario was her simply coming to the user and password screen to unlock the blank screen screen saver. She took it as a reboot and relogging in. This had gone on for months and four other technician that all deduced she was an idiot. I offered an explanation with a light and understanding attitude, removed the password protection of the screen saver and offered her a much better screen saver... 3D Pipes

I listened and she's happy.