I'd like to buy a drive today or tomorrow, but not sure if spending any extra on a faster SATA drive versus a cheaper one is worth any amount of money. Seagate perpendicular drives are supposed to be higher response, WD claims 8.5 ms avg seek times - is it worth it?
I have a KuroHG, not a Kuro-Pro (so please ignore my beer-fuelled ramblings if you want to).
But... in any computer system there's a limiting factor to the system's performance. Good though the Kuro is, I'd suspect that it's limiting factor is the Kuro itself, not the hard-disk you connect to it.
I wouldn't bother too much about the hard-disk, other than to select a device with a decent MTBF and one whose manufacturer you trust with respect to reliability.
True, there are some really fast drives available, but the hardware of the Kuro, and the software likely to be installed on it, probably aren't able to keep up with the best of drives. If you need super-duper performance, the Kuro probably ain't the best choice. For me, it's a device more suited to an "always available, little trouble" machine rather than being a high-performance beast.