I did the same but also used a recorder. I didn't try the recorder until half way through school and it was really helpful. I rarely had time to relisten to whole lectures in fast mode but made time for certain difficult lectures and fine tuned my notes while listening. Whenever I found myself drifting or I didn't catch something I would write down the time from my recorder in the margin of the page and then I could go back and just relisten to that portion. I would also relisten during exercise or in the car for certain things. You can also record your own voice with specific study material that requires memorization like lab values and replay them during exercise or driving time. At the end of each 5 week course I would load it onto my computer to clear the device but not lose the info if I needed it.
That pen sounds awesome, though. I would try it. Sometimes I would need to relisten to something on my recorder and not be able to find it. That pen sounds like it would solve some problems and make it easier. Hope it works.
The one thing I was never able to resolve was finding a program that would take my audio files and change it into a text file that I could print out or finding a program that could make a text file from a 3 hour lecture. But I may be a lttle behind the times. I have to have paper, write things, underline things, highlight, draw pictures, etc. to learn.