I'm wondering for those who have both a ssd and hd, or dual ssds, or dual hds, how much battery life do you think you lost compared to when you had a single hd or single ssd? I have a data doubler in my macbook and get only about 4 hours of battery life on my mac (with very little video watching) just browsing news sites and email. I'm running mavericks and the battery is 4 years old at ~85% health. With snow leopard and a single hd (same 85% health), I used to get 6 hours battery life, but that was nearly a year ago. I'm not sure if mountain lion or mavericks is going to make battery life worse than snow leopard. I no longer use my macbook for work, so I don't need as much storage, and could put the doubler in an old mac mini which does have a very slow hd. Do you think I'll gain an hour or two more battery life if I remove either the SSD or HD and put the dvd drive back in? Thanks.