I use the shareware version of SharpEye which is fully functional as far as I can see, except that it will not allow you to edit the lyrics associated with each system. Apart from that I thoroughly endorse Lesley's thoughts. I haven't used MidiScan because (as I recall) it is so crippled in its shareware state as to be untestable. With good quality input the degree of corrections with SharpEye can be minimal, even for a complete Grand Staff score.
I'll ask Alan if he wouldn't mind posting a .BMP file or two to the MUDI site. That way anybody can try out the scanning software without the need for a scanner. SharpEye requires .BMP or TIF files (black and white only - no greyscale permitted). Lesley, are the needs of MidiScan similar to this?