I did the first blended Biomedical Ethics class summer before last.. it was only moderately successful... they mostly did the on-line work, we had mostly normal classes and the only reason it was a blended class was because we needed to smoosh it into a time slot...
After that, I did a hybrid class where the students came 2 of 3 MWF class meetings, and I did all three --so, they did an hour's worth of on-line activity and I increased my workload by 1/3. The idea was that smaller class sizes for part of the class would increase class discussion and participation... but, not really.
I tried it again this past summer with about the same results. Now i'm starting three Ethics sessions that meet 75 minutes per week in person, with the other half on-line. Now I have an afternoon and a whole Tuesday to do their grading -- and I see them on Wed and Thurs -- with Thursday being THE Ethics day... with a 2:15 section and a 6:00-7:15 section.
I like this arrangement because it makes them write more -- which means I grade more... but, now at least I have the time to do it.