I went got me a set of the Z customs about 7 months ago and I have to say I love those things and have had the notion of replacing most of them with the Z's.
I guess it really comes downt to what you are wanting to play, but the HH are great. I play in a band that right now that plays a little of every thing and they seem to blend in nicely unless you are using an open close sound on them and trying to play soft then they come out a little loud but other than that I love them.
When I was trying to choose what I wanted I looked in the
zildjian book that is usealy right in front of the cymbals in a music store and found some of my favoret bands and looked at there set ups to see what they had that I liked to hear in their music and I basicly just mis matched from there.