Karate Monkey considerations

I have one that served as my commuter for a winter, but is now full time single speed trail bike. Some things to take into considerations:
1) it will take discs and V-brakes. Discs in the rear with horizontal track style dropouts means you have to loosen the brake caliper mounting bolts to remove wheel if you get a flat. Not a big deal, just an extra step. Can be avoided by running V-brake in rear, and disc in front. Still plenty of stopping power in wet conditions
2) Fenders and Racks for Panniers plus disc brakes can get tricky, as mentioned above. You'll have to get creative with mounting hardware.
3) THE KM has very short chain stays, which might be a consideration for panniers and heel strike. I have no experience in this though, I used a Nelson saddle bag
4) Running gears: SOme front derailleurs can be problematic in terms of hitting the rear tire. Surly's site has info on this, and their fix for it, the "monkey nuts". I ran mine single speed so have no experience with this either.

I love the KM. It is one of the most versatile bikes out there. I built it up with big fat Big Apple tires and it was one nice urban assault bike. Since it is now my dedicated trail bike, I ended up with a cross check as a commuter, cuz it will fit the big apple tires too (the 2.0 in width ones, not 2.35).

If it's disc brake capability you want, but you want a lighter more road-oriented bike, i think there are some cross/touring frames out there that have disc tabs, one that comes to mind is the Kona Sutra.