Well, I have actually owned both, in fact, I own both now, but the Black needs a retipping.
I have the previous version of the Statement (the 2.5k one not the 3k one) and I will say that it actually sounds in the same realm as the Koetsu house sound, it is closer to that house sound than lower Grados. The Koetsu, being an MC, has a lovely midrange but its highs are sometimes etched out, not as natural as they should be (higher models of Koetsus improve this as well as providing more extension).
The Grado has a sublime midrange and a top end that is never harsh, but is extended. The bass is generous and tight, never out of proportion with the other frequencies.
I don't have much experience with carts, but from what I have heard the Grado is the best. It is also the most expensive I've had in my setup, 1k more than the Black.
Price isn't everything but if I were to have 1600 and I could buy the Statement or the Black, I would go Statement.