As I accidently started this great snorkle debate, guess I will jump back in. I also perfer to cover long distances on the surface on my back, hence the lack of need for a snorkle most of the time. I find that I can make more efficent kicks due to my entire fins being under the surface and I enjoy the time to chat about the dive. Having said that, if the water is rough, then turning over and using the snorkle is the way to go. If I think there is a chance of that, then the snorkle goes along, just attached someplace other than my mask. As for going in the wrong direction, agreed that can be a challenge but I simply find a landmark to reference my travel on or if none are avalible a compass heading works just fine.
Martin, did you get the information you needed? Sometimes this crew gets off on some wild tangents.