Covering the lower end of what line? Cameras or ISO range?
The K-5 has remarkable dynamic range, particularly at ISO 80 and 100, but is exemplary to about ISO 800 to today's sensor standards. The K-x, I feel, was Pentax's break into excellent dynamic range throughout the ISO range all those years ago.
Shadow recovery is important (to me) because a lot of what is done in PP to improve images comes from recovering this shadow detail. Highlight detail is significantly harder to recover when pushed too far in an exposure, as is common for high contrast scenes, like daytime landscapes.