I'm giving up on the wake from standby mode problem for now. I am unable to provoke this problem in my application. What's more, if one adds paper to the scanner in bin, the scanner comes out of standby mode by itself. And this is what an operator would normally do before starting a scan.
Another big issue is that my client is insisting I deliver the scanner and app next week. I'll see if I can get some code to do detection of the scanner properly in standby mode tonight. -Philip