My advice is do not buy an XGK. Given your scenario, I have no idea why you would want one. I own one and consider it one of the finest stove designs ever made. BUT, it is not a stove for general camping. It is a mountaineering stove. Mine is the older, round one and looks nothing like the new ones, but I don't think there is much operational difference. Jason can correct me if I am wrong on this point.

MSR is a great company that supports their products, even the old ones like my stove. The XGK does one thing and does it well. It runs at full blast and sounds like a small jet engine. It will burn any flammable liquid you are likely to find (including stuff they tell you not to use, but listen to them, not me). However, if you want to do anything that resembles actual cooking, it is not the stove for you.

If you want a multi-fuel stove, both Primus and Optimus make them. I have an Optimus Nova, which may be more versatile, but I don't consider it as reliable as the XGK. I also have several other stoves, including two canister stoves.

I've seen the Reactor, but know nothing about it, so no comment on it.

What I usually take on my trips is my Nova and a Primus Micron canister stove as a backup and day hiking stove. I see little point buying two of the same thing unless you are in a big group.

As for your reasoning for carrying two stoves, the solution to running out of fuel is carrying more of it, not another stove. I can field strip my Nova and have done it in freezing cold weather to fix a problem. The only thing likely to actually break on a stove is the pump unless you do something really bad to it. The more likely scenario is a clogged fuel line or frozen fuel filter. Canister stoves don't have this problem-no pump, no filter.