I have a 300 win mag in an A-Bolt that is light, accurate and easy to live with unless you are an elk, moose, caribou, red stag, tahr, etc. and the recoil is ok. An ex-hunting buddy insisted on getting the 300 RUM. In the end he just wasn't experienced enough to manage the recoil and the rifle was a lot heavier than mine to boot. On game I noticed that his caribou died just like mine did. He ended up putting a brake on it which I insisted he not use when hunting with me after he fired the rifle once when I was nearby and without hearing protection. We don't hunt together anymore. He was too terrified of the rifle to hunt without it and I like my hearing. I shot it and man it does kick hard and very sharply but it's not impossible to tame. The weight and power overkill was more of an issue than anything for me.
I think the 300 RUM is a powerful and useful tool for bigger game at longer range. Just recognize there are trade offs in weight, recoil, etc. For me, they don't compute and I'm sticking with what I have.