I travelled in a Sleeper coach in Rajasthan, and had to travel all the way cursing my decision! The sleeper berths are too short in length for tall guys. And, each-n-every bone in body protests over the abrupt undulations on rough patches! Trains are better for a journey where you wish to cover it while sleeping.Can't comment on sleeper buses down South, but up here in North, they aren't all that good or comfortable. In fact a few of my relatives, who have traveled in them, prefer normal Volvo buses over these sleeper coaches.