Interesting setup. A question:
Why aren't you putting webserver traffic into 1:20 or even 1:30 and Skype into 1:10 and let it borrow bandwith from 1:10 when it's available. This seems to me like a much simpler approach and it doesn't limit Skype as much (it can then use as much as needed).
Also, putting webserver traffic into the high priority class will potentially slow down ICMP traffic I guess.