An 8 Channel 3Ware Escalade 7500-8 or 8500-8 can easily saturate PCI64/66, and they also have 12 Channel versions.

They use ATA for the drive interface, but have a proprietary "switch" that allows addressing and full UDMA133 / ATA150 access to the drives simultaneously. In a RAID0 situation it can easily saturate the entire bus. So that's when you use PCI-X and get a Bus per slot hehe.

RAID5 is a little slower, but you can average about 200Mbyte/s read and about 120Mbyte/s write

They are pretty slick, and are awesome in action. One of the Escalades with the new Maxtor 1 Million MTBF near-line commercial IDE drives, and the sucker will last a life time.

Oh and they support hot swapping of the drives.