I just installed this unit yesterday. Eclipse fixed some of the issues that bothered me on my CD8455 (not being able to easily adjust the subwoofer volume in Pro-Mode, and changing tracks with the rotary wheel).
I am currenlty using in it in the 4sp+sub mode, which uses front and rear speakers, plus a subwoofer. In this mode it has a 7-band parametric EQ, time alignment, and fully adjustable crossover (can pick different frequencies and slopes for the front, rear, and sub). In the 3-way mode it will give you the same features, but the parametric EQ has more control. It will have 5 bands for the highs, 5 bands for the mids, and one band for the lows. This is one very nice head unit. I am going to pick up a Sony memory stick to play around on Eclipse's website. Too bad they do not include them with the HU anymore.