Just had the XGK EX sent from REI to the Czech Republic. Tested it out on my recent trip to Chamonix and have nothing but good to say. Solid base, transitions from priming mode to burn mode quickly, not much heat loss from the base (i.e., cooking on snow not a big issue), burns multiple fuels well, love the flexible tube.
Improvements over the old XGK are (1) flexible hose, (2) excellent transition from priming to burn mode with decent flame control and (3) the base legs (see picture).
Burned both white gas and diesel very well.
Still the issue of simmering adjustment, but it's a clear improvement over the time tested and excellent standard old XGK.
This is the only way to go if your thinking about a versital stove.It is able to burn anything that you will be able to find in, any nation that has some form of fuel. It is great for high altitude at, least as high as I have been so far. Very easy set up and little matience. Mine came with a nice little stuff sack. It is very light weight for the amount of power that you will get out of this little guy.
I used it on my Aconcagua expedition this December/January and had mixed feelings.. it worked great up until about 18,000ft - at which point it was extremely difficult to light and keep lit. I needed to use it to melt water at a little over 22,000ft and it was a struggle to say in the least...
I have it for 5 years and i only changed some o-rings at the pump, so the spare parts kit is advised.
I used it for 5 days in Mont Blanc during winter at 3600m, -20 degrees, and it was ok for 10 persons. It is really powerfull, we all had a big pot and that was it.
Like any liquid fuel stove it takes some time priming bu once burning nothing can beat it.