One of the central struggles of a Sudbury school is reconciling individual rights and freedom with community rights and needs. I can't speak enough of the importance of this struggle. A drop-in center and internet classes simply can't incorporate this aspect in the same way. I personally have found that despite my belief in children's right to self-determination, it is very challenging as a staff member to see things from the students' perspective. It is especially hard to sit back and watch students decide something that seems so clearly a mistake, based on your adult experience and knowledge, and allow them to learn for themselves the hard, and long, way, in particular when you think it is a decision that might be harmful to the school.
Some kids spend a lot of their time just getting used to having power.
The actual rightness or wrongness of their decisions is secondary to them in comparison to having the freedom to make those decisions. I can't imagine having lots of adults around dropping in as students and bringing all their adult perspectives and baggage. I would be afraid that it would really harm the balance of power, among other things. Having said all this, I acknowledge that I have not done research on this subject or tried to develop a school like this. Perhaps the goals would be much different from those of a Sudbury school.