I studied for both as well. I decided to
take the 2015 simply and solely because of
less physics, less ochem, more biochem = not more material, same amount just differently dispersed across categories
and if you took both tests and did well, why? Why would you take both exams if you did not need to?
Harder process? meh. More people alive today than 30 years ago, yes. More people applying? the %s are similar. Not sure that makes one or the other harder.
Not more material? Did you completely forget about the fact that they added a 4th section, the Psychological, Social, and Biological Foundations of Behavior? Also, there is a significantly higher amount of biochemistry on the new exam, while physics and general chemistry were left relatively the same (even though the percentage of questions on those topics on the physical sciences section was reduced).
I took it again because I wanted to apply to some higher tier medical schools and increase my chances across the board.