Guess ours wasn't an Express (l0l) - we stopped about 6 times or so along the way. We had an express though on the way back and don't remember if it was Tulum or not. We didn't find it made a huge difference timewise - maybe 40 mins tops between the two bus rides.
Just don't remember all the names - definitely some smaller little towns were some of the stops - but they looked quite charming.
Cheers.
Connie