Ask on the AOPS forum for comparisons of the classes. DS is doing intro to geom right now and finding it challenging - even though he's in principle known the material for a while - but not immensely time-consuming (yet); maybe a couple of hours a week.

Can he use a computer in class? If it's possible, then having him use Alcumus rather than follow a class would give you a lot more flexibility.

Email: my username, followed by 2, at google's mail