I think that one way to answer your queries is to share my own experience.
The K-7 was the previous Pentax flagship with a number of semi-pro features. However, it was also my first dSLR and I did not buy it for the technical features. I bought my K-7 for the built quality, the weather resistance, the viewfinder, the handling and its performances (eg Hi continuous shooting). I was not disappointed and I love all these. In fact, the K-5 re-uses basically these same features from the K-7. It says a lot
In addition, I learned to love the more advanced features of the K-7 with time. True, I do not use all the features, but there are available if and when I need.
What do I miss? Not much! The K-x, K-r and K-5 have better high-ISO performances. But neither the K-r and K-x have the handling and built-quality of K-7/K-5. Exit the K-x and K-r. That leaves the K-5. If I had the money, would I upgrade for the K-5? Yes.... but I selected to invest in good quality lenses instead and I do not regret my decision. (A camera looses rapidly its value, being replaced every 12 months. A lens does not.)
Hope that the comments and experience will assist. Go for the K-7. It is a fantastic deal right now as it is replaced by the K-5.