Energy drinks make little to no difference for me, its like alcohol for some people, they just dont get affected as easy at others, a friend of mine hadnt drank a sip of alcohol other than 2 beers on his 18th birthday, on his 20th bday he went to the pub and easyly drank everyone under the table and kept going and he is a fairly small guy.
A place i used to work got like 25000 cans of redbull/redbull + coke that needed emptying and to be made into place mats for a promotion thing so i ended up drinking nothing but redbull for over 2 weeks (no coffee, no juice, and water only if i woke up in the night and needed a drink to clear my throat like i usualy do) and i was fine.
I got through generally around a crate of 24 a day just while i was at work and i took some home with me on the evening/weekends and then took the cans back in with me.
It didnt affect me in any negative ways at all from what i noticed other than needing to pee more for obvious reasons, my resting heart rate only went up 1-2 bpm over what it was on average the entire week before i started drinking it, i didnt have any problems sleeping/waking up in the morning, and all my teeth were/are still 100% fine, the ONLY down side i got was a muscle memory reflex thing from taking a sip so often but as the water cooler was by my desk i just got a bigger cup and kept filling it up with water and that had pretty much vanished after like 10-12 days.