im about to buy the thor m2 and it comes with 2 16340 batters so I was wondering if I can put a 18650 in it and if I can is it better to do so or is it better to use the 16340's it comes with in terms of batter life, power out put and so on. maybe some pros v cons on each one if you even can use either one. also what batter would you recommend as a back up batter to switch between charges