Echoing what GeneralSoybean said, this panel is clearly outperforming the Shap Panel on Dell XPS in many metrics, and the Sharp panel on XPS is widely regarded as the best 16:10/15' panel available. Given that it is likely Dell has the best access to top-end Sharp panels due to their long relationship (XPS series have been exclusively using Sharp IGZO panels for years), it is easy to see why HP went this route.
This panel does not even show up on panellook, so it might be a "HP special" from LG, even. BTW, I use the new Zbook Power myself (a very good laptop), and the 1920*1080, NTSC100%/8bit panel I got with it does not show up on PanelLook, neither -- I think, it is a pretty good panel aside from its poor default calibration.
About the price, well, nobody should pay the stated price for the custom-configured business laptops from HP. Places such as B&H have pre-configured models available which are more reasonably priced. The HP website sometimes runs heavy discounts of BTO models, which is how I got my Zbook Power. Note that Zbooks comes with 3 years international warranty (which also has the much better support than their consumer products), or have it available as a cheap upgrade. They also have the excellent long-term support, my old Z-book kept receiving BIOS-updates for years. If you depend on your laptop for your job, the great warranty and supports are worth far more than, say, having a bit faster NVidia GPU.:)