Yeah, I keep coming back to that... I'm currently using a 20" Evolution Ride as a crash and it's pretty scary! But it just isn't fast enough... I was toying with the idea of an HHX 20" Xplosion earlier, but that cymbal doesn't have a sound clip on Sabian's website and I've never seen one in person.why not a darker crash to round out the set, a K Thin Dark or some thing similar, seems you already have the bright sounds covered with your projections...
Actually, what is K Thin Dark? Is that a crash? I was looking over Zildjian's website and didn't find any K crashes larger than a 19". Then again, they don't list other 20s that I know they make. That may take a little extra investigation...