the premier line has better preamps and better internals, but other than that, they are identical

Now that I've had a week or so with my P480, I'd say the P5800 you're considering is probably practically identical. I am convinced that all aspects of its operating controls and buttons, including iPod control with the CD-IB100 is 100% identical to my P480, so you might as well geet the P5800 and have some red lighting instead of green, and just turn off the annoying organic display animations. (Why manufacturers think we need our HUs to have an animated display baffles me.)