I expressed the same concern with the advisors at my school. They said the old books ("current through spring") can be useful, but I wasn't really satisfied with that answer. So this is what I answered back:
As one of the first students taking the new MCAT, I want to have every bases covered and I want to make no mistakes. I also want to abstain from wasting time, money, or missing important information. Therefore, with all due respect, I would like to be certain that the books I own, the ones you refer to as current, have more than just the potential of being useful. I understand I will have to purchase the materials covering the humanities section, but will the 2014 science books (chem, bio, orgo) be commensurate with the 2015 science books? Would you endorse making a 5-month study plan with them? According to the 2009 MR5 report (the report that gave rise to the 2015 MCAT), certain sections such as general chemistry and physics scored below average on an importance rating, thus making me believe that questions on those topics will become less pronounced or perhaps altered in some way. Even more concerning, the AAMC and Exam Krackers have not mentioned anything regarding using old books or buying new ones. This is why I am concerned.
What do you guys think??? Any thoughts?