Yup, as I said you can always pack extra power if this is rarely an issue. But I also think that, if you are regularly going to run the battery dry, lugging extra power means you picked the wrong watch. Personally, when I'm out hiking, I would very much prefer to not add two pounds of spare battery to my pack even for one day, let alone 7. If your usage falls squarely within the battery life of the Epix, I think it's an easy choice. The screen is much, much better. If your usage falls squarely outside the battery life of the Epix, I think the Fenix is an easy choice. The screen isn't as good but functionally the two watches are really close.
I took that last paragraph as my deciding factor and ended up getting the Epix Gen2 Sapphire. Love this thing.