In the document Oculus_Developer_Guide_0.4.3.pdf, page 22, some 'typical' values for positional tracking volume are specified. It should be said by calculation that the volume has an area of 3.77m(W)x2.55m(H)@2.5m(from tracking camera) and 0.60m(W)x0.41m(H)@0.4m for DK2.
For instance, the height 2.55m sounds enough for covering various positions like lying on the floor, sitting, standing (and even jumping!).
But it will be done only @2.5m. Your head position will be lost if you step back from the camera, or your operational area will be limited if you get close to the camera.
I think it's nice to be able to provide an environment, for example, that allows a user to look at various surfaces of an object by walking around it because that kind of experience will hardly be done by just a single flat panel display. What do you think about the current setting for positional tracking volume - is it enough for your (or your favorite) apps? Is there any smart way to expand it? It would be an important issue when we are concerning about the mobile VR.
BTW, a brand-new Crescent Bay prototype is said that it has an expanded positional tracking volume. I don't know about a typical volume size of it, but I hope it supports wide and deep area.
It will have to be tiered, for production reasons...
eg.
Desktop/sitting - Single player Room/standing - Multiplayer Building/roaming - Massive Multiplayer
Taking baby steps in VR dev work is probably well-advised. We hardly know how to do Single Player VR right now, so the specs you listed are a really accurate way of saying where we as a collective should be focusing our efforts.