I don't know if this issue is of any interest for your website as I read about your plans of releasing the strumming CD. All I can say ist that I can both strum and pick a little and that the song lessons here are quite possible for me to play after doing some practice. But I found out that more complex and fast strumming that includes muting and and changes in the speed of playing are nearly impossible for me to do. My last attempt was to play some Dave MAtthews (like dancing nancies) and I just couldn't do that. And that happened to me so often that I just couldn't get a more complex strumming thing right. I think you will cover this with the CD but an online lesson would also be a good thing (no matter what song you choose).
Sorry I didn't get to reply to this earlier - I think you'll find the upcoming Intermediates' lesson (REM's Driver Eight) will help you in this direction. Granted, it won't be anywhere near as complicated as Dave Matthews, but at least it'll be a start. I hope...
Peace
Thanks David. Looking forward for the lesson. I guess Dave Matthews is just a bit too advanced for me. I know I should be be more patient and happy with what I already can play.