My experience at those ranges says the 12 would be fine. Usually lose field of view as the power goes up. Not sure if your worried about that. Just my opinion.
I have a Yeti 120 and Rtic 65. Last year I fit a whole boned 6x6 elk with ice in both no problem. I would not spend the money on a Yeti again. The Rtic coolers are just as good (my opinion) and a lot less money. They even just came out with some bigger sizes. The bigger coolers can be heavy when...
They way I understand it is this. The bullet speed does not effect how long it is in the air. It does however effect how far it travels before it hits the ground. This is why a faster bullet has a flatter trajectory. Am I wrong?