Douglas, to me it seems like a waste to use full frame lenses on crop cameras, it means that the lens will not be as wide, or as fast or as small or as cheap as it could be (or all the above). IMO this type of camera is meant to be used with the pancake lens it was designed for, otherwise its form factor is ruined. And the whole point of this camera is the form factor, otherwise why not get a DSLR instead...
But Ι guess if you have found a lens or lenses that work for you on this camera then truly it isn't an issue. Personally I'm a 35/2 kind of guy and I'm struggling to achieve this combo with crop cameras and pancake lenses.
Well, there is no lens smaller than my MS Optical Perar 35, if size is the ultimate goal. That's the beauty of it all, really. Versatility.
-If I want to go super small, I bring the Perar.
-If I want to go regular small, I bring the ZM 35/2.8 or Contax G 35.
-If I want to go with smallish, yet fullish system, with a tiny bag, I bring either the ZM 35/2.8 or Contax G 35, the Sony 16mm and Skopar 50/2.5.
-If I want to go with a full setup in a small-medium bag, I bring the Sony 16mm (with wide converter,) Contax G 35, Skopar 50/2.5, Contax G 90, Zeiss Jena 135/3.5
-If I want a small, lowlight setup, I go Sony 16mm, Nokton 35/1.4, Nokton 50/1.5
I've really got about a million combinations, depending on where I'm going and what I'm doing. It's all about versatility with NEX.
Really, the only hole, like you mentioned, is the 35mm (equivalent) lens, but the Sony/Zeiss 24mm, which is rumored to be f1.7, is coming this year, according to Sony, and that is probably the only other native e-mount lens that I'll buy.