Originally posted by Deedee So really K-5 or K-5II?
I encourage you to go for the K-5 II.
The AF not only works in very low light (-3 EV) but stays accurate in such low light levels. The K-5 can produce front-focus in low-light situations.
Furthermore, the AF of the K-5 II has an f/2.8 sensor in the centre, meaning that it will be even more accurate with fast (wide aperture) lenses. The K-5 has accurate AF as well, but the K-5 II is even better.
If you are not planning to replace your camera with an updated model soon, I'd definitely spend a bit more money now and then reap the benefits for as long as you own the camera.
BTW, I've been using a K100D and just upgraded to a K-5 II. Brilliant camera. I'm sure you'll love it.