It seems that the buses are rated slightly higher at AK, compared to OKW from what I can gather.
I was a little worried because we visited Jambo House with friends last summer and waited over and hour for a bus from there to Hollywood Studios. We ended up getting a cab, but the bus pulled up right as we walked off. It was a nightmare with three kids 6 and under. I am sure it was an unfortunately and rare thing, but it definitely had me worried..