Against what more one might see, one has to balance the hassle factor.
This was the deciding factor for me. I sold 20 and 18 inch Dobs for a 12.5 incher. With my 12.5, both feet are always on the ground, set up, take down, storage, loading into the vehicle are all easily done. The others were a huge hassle, and caused me not to want to get out and view. Not so with the 12.5.
That's a decision many people have come to, including me. The improvement in the view through a 16" scope is not proportional, for me, to the extra hassle of transporting the larger scope to a dark sky site. If I could view from my backyard it would be a different story. The jump in size from even a 12 to 14 inch scope is much more than the 2" difference in mirror size would suggest. But if transport is not an issue, I would definitely go with the 16" scope - every extra bit of aperture helps.