Don't forget to take into account battery life as one key parameter to select a camera system to be used in the Himalayas.
At least from my experience in Nepal a few years afo, it is not always possible to recharge batteries in every lodge in the Gokyo/Chola/Everest base camp area. Besides, there are typically few power plugs and then tend to be in high demand.
I was really happy to have my D3 with a very high autonomy and a double charger.
I have never shot with the X100, so this is not a negative comment about it, just be sure you have enough batteries considering the environment you'll be shooting in.