I think if you own D2 knives (or anything above 60 on the Rockwell hardness scale for that matter) that you will find they are much easier to maintain if you do so frequently. Of course this is true with all knives but with the super hard ones it is perhaps more important to know.
Light sharpening on a frequent basis using a strop to keep that edge in shape is not so bad with the harder steels. In fact in my experience it is usually better. Lets say I have an AUS8 blade and a D2 blade side by side and make the same amount of cuts on something. After several minutes the AUS8 blade would undoubtedly wear more and roll the edge and perhaps show signs of dulling more than the D2 blade. So, the D2 at that point would most likely be easier to strop back to sharp because it has less wear. The D2 blade may be back up and running in three strops per side and it may take eight or ten for the AUS8 blade to do the same. D2 and/or these other harder steels like S30V don't start to show their 'bad side' and get to be a real pain until it comes time to do 'radical' sharpening on them which should be very infrequently if you maintain it after use.
For example, a wood carver like myself, typically carves on hard woods for 20 or maybe 30 minutes or when the tool begins to feel like it is dragging through each cut. At that point he then strops his edge to bring it back up to the level of sharpness it was at when he started carving. If he just kept using it, and using it and using it without this periodic maintainance of a few strops now and then it would eventually get to the point that the edge would require much more time to sharpen it and it would be more difficult to do also.
If you are one of those types that lets his knife get really dull between sharpenings D2 is going to end up being a bad choice for you IMO because when it gets dull it wears so well that you will be sharpening it for a good while in some cases. But then again, just about anything else in cutlery will too probably in a lot of cases.
With a little routine maintainance you can keep that edge in top shape a whole lot easier regardless of whether your blade is 420HC or ZDP189. When you get a very nice 'pre-sharpened' factory edge on something like a Spyderco 30 degree super cutter, or even a fine kitchen knife the best way to keep that edge in top shape and in some cases actually take it up a notch is to adopt a routine of periodically stropping it on both sides using a good polishing compound and a leather strop. I personally like the FlexCut Gold polish compound. You wipe it on your leather strop just like using a crayon. One bar lasts forever.
When I say routine maintainance, I'm not referring to sharpening stones. On an edge that it already highly polished stones and diamonds just scratch up that polished edge and actually reduce the sharpness. Stones and diamonds and such are not really necessary until it is time to reprofile an edge bevel. Or correct chips or damage to a secondary bevel or something of this nature.
I know this is repeat info for a lot of you guys. Forgive the rant. I just thought I'd throw this out there again because it shows in a very profound way what stones do for an edge and what stropping does. I realize that some people like that course edge and it has it's place so if you are happy with that I'm not suggesting you change a thing. Just stating how I like my edges.