When I'm out travelling, I'll be using quite a few buses, so I'll have an Explorer in my pocket ..... at that point, buying an additional ticket to travel between two points that are also connected by a bus route becomes just an additional expense, despite the speed differential.
Having said that, slowing the route and halving the frequency does make me somewhat rethink where I might go on my days out!
RE: How successful has Xlines been?