Digital BW, The Print

I have lurked on this board for perhaps several years, learned an
immense amount, but never posted.

I have my own gallery website where I exhibit and sell my own custom
B+W prints.

As an extension, I am wondering if anyone has experience and feedback
selling images through the major online stock photography websites,
such as: istockphoto.com, shutterpoint.com and stockvisuals.com.

Looking forward to learning more. Thanks. Mike.