I have a 1911 Karbine, which is similar to the K31. The K31 is a better gun in that they moved the locking lugs forward, and shortened the receiver by doing so. Other than that, they are pretty much the same. The straight pull is pretty cool. It takes some getting used to, but it works great once you've got it down. The big knob and the huge safety ring are easy to operate, even with winter gloves on. The magazine is detatchable, but it is designed to be loaded with stripper clips, not by swapping mags. Typical Swiss high-quality. It works great and shoots great. Ammo was too expensvie, but they're bringing in surplus stuff with the rifles. It's still not cheap, but a lower price than the Norma fodder.
If you're into old miiltary rifles, I'd recommend you get a K31. They are certainly different, and they are fun to shoot. The K31's that I have seen are in VERY nice condition. I mean they are far better than most of the run-of-the-mill surplus guns. I've seen various prices and conditions available, so I assume you get what you pay for. Try to get the best one you can afford. It will be worth it.
Ross