I used it for a little while, It didnt seem to affect my battery at all but initially you could just plug in the headphone jack and it would cut it off. I think they have fixed it. Personally im never more then 3 ft away from my mbp while in a coffee shop. I spend about 4-5 hours a day working in a coffee shop and i learned my lesson to never take my eye off my stuff. About a year ago some guy attempted to jack my laptop while i was getting a refill, Luckily an employee was close enough to stop him. I would have lost everything and i also learned the potential value of backing up lol =)