I had the same questions you did. For me it was the
X-lander Military vs the
Core black and yellow. In my case the application was multiday cold-weather alpine mountaineering. The
Core model was very attractive because of the storm alarm and the sunrise/sunset times (good for making the ever-painful call to abandon a summit attempt). The interface looked great too!
In the end, I picked the
X-lander Military for the following reasons:
-The screen contrast on the
Core is dubious, which is bad for a watch that's supposed to be read anywhere at any time. This and a few other things give me the idea that marketing, not engineering designed the
Core. Screen contrast on my neg face
X-lander is really good....suprisingly good.
-The
Core is made in China as opposed to Finland for the
X-lander and reports have suggested that the fit and finish on the
Core in not quite up to classic
Suunto standards. This wouldn't matter so much except that I don't need a risk of parts flying off my watch or things coming unscrewed at 12,000 ft on Mt. Rainier. The fit and finish on my
X-lander Mil is excellent. Definately feels like a $350 insturment.
-A waterproof-button
X-lander aluminum is $350. A waterproof-button aluminum
Core with a LEATHER (bad for water)
band is $400 + price for a rubber
band. I found the screen contrast on the aluminum model to be unacceptable.
-The internals of the
X-lander are very proven. I decided that the fundamental soundness of the basic function of the watch was more important than graphs and extra features, however handy they might be.
-I had concerns about the bugginess of the
Core models.
-The size of the
X-lander is not that bad. It's really not.
In addition, I've found complaints about the dim backlighting and faint alarm sounds to be a bit overblown. The alarm could use a snooze alarm, but oh well - usually after a cold night in a bivy sack, I'm looking forward to getting up anyhow!
These are just my views though. Everyone has their own required mission for their insturment. Hope this helps though!
May you get good use out of and enjoy which ever you choose for yourself!