My SE Delica ZDP was the sharpest SE knife I have ever handled. I haven't used it that much yet, but it has done a great job on zip-ties so far. I am going to rotate this one into the lineup more often to see how SE ZDP performs.
I have a little more experience with PE ZDP, and I will agree that it is a pain to sharpen! My Caly 3 was the sharpest knife I had ever handled - the original factory edge was way better than any other I have used. Amazing push-cutter. When the time came to sharpen I used coarse stones to set the bevel, and then the Sharpmaker to apply a microbevel. The results are good/satisfactory, but not up to par with the factory edge in terms of push-cutting performance. Usually I can improve on the factory edge, but not on this one! I have a harder time getting a polished/push-cutting edge on a ZDP knife than with other steels, but slicing performance is excellent.
Soon it will be time to sharpen my Caly Jr. ZDP, which was on-par with the Caly 3 for out-of-the-box sharpness. Absolutely amazing cutter. The edge retention on this Caly Jr has been awesome. I am looking forward to seeing how my sharpening effort turns out.
I also have a D4 ZDP PE, which came with an average factory edge. It was rather obtuse, and I had to remove a lot of metal to lower the edge angle. On this one I was not happy with my results, and sent it to Tom Krein for a regrind. He does great work, and he also made me a great neck sheath for it. I like the VG-10 Delica in factory form quite a lot, but the grind and edge are not optimum for ZDP, in my opinion. With the regrind, cutting performance is increased, and re-sharpening will be easier.
Tom put a .010" edge on my D4, and it is an amazing cutter. Has anyone measured their Calys to see what the factory edge is on those? Based on comparing it to the D4 regrind, I am thinking it can't be that much thicker b/c the performance is great. Maybe in the .020" range?
It was quite a bit sharper than the PE version that I own. 
I just have a hard time to get it sharp; one problem is that the angle on the right side seems to be around 40° incl., so even with the 40° setting of the sharpmaker I run into difficulties when sharpening. The left side (with the bug) is ok though.
