interesting subject. I just tried what you have said and found that scanner profiling module does better for scanner profiling and digicam module does also better for digicam profiling. I am not sure how you did your scanner profiling and what your scanner is, but in my case the scanner profile generated using Kodak IT8 target using reference values custom measured with SpectroScan works excellent. It is quite accurate.
Regarding scanner profiles generated with digital camera module, in short the results have much less contrast. I used reproduction, general, product options for profiling.
In the case of digital camera profiles using scanner module, the result is not that bad, most similar to the one created using reproduction option for profiling. But this time again camera profiling module works better for digital camera profiling.
I guess the much wider dynamic range involved with the digital camera capture which is supposed to deal with the real world, not just fixed environment like that of scanner, makes the difference.
I am using ProfileMaker 5.0.7.