I'm going on a trip to South America next week and I plan on doing a LOT of shooting...possibly up to 6+ hours a day of actually taking pictures. I know I'm going to have battery issues so I'm looking for some help. A couple of options are just buying a few more NB-2LH batteries (the standard Lithium Ion batteries) or investing in the BG-E3 battery grip which can hold (2) Lithium Ion batteries OR (6) AA batteries (although this is recommended for emergencies only from what I've read). I really don't want to miss out on some great shots because of a dead battery. I want to know what I need to be safe. To clarify, I will be able to charge batteries at the end of each day. For those of you who use battery grips, how much battery life do you get out of those? Otherwise, how many Lithium Ion batteries should I bring with me to be safe for 6+ hours of shooting. Also, are knock-off (ie. non-Canon) batteries any good or do they die quickly? I appreciate the help, cheers.