Mac-based High Performance Storage Solution Needed (Areca)

I have a 16-bay server enclosure running XP Pro and an Areca ML1661, 16-drive SATA RAID card, running in RAID6. I need to switch this over to something Mac-compatible and I need to reduce noise and power consumption.

It's for mixed home / business use, primarily storing media. The final solution needs to be able to recover from the loss of two drives simultaneously. Ease-of-use is important, but read/write speed trumps this. I'd also like the solution to spin down fans and hard drives, whenever possible.

I've considered dumping the Areca for a Drobo Pro or two, but think I might be losing too much speed in doing so. I've also considered putting the Areca in a Mac Pro with a PCI-e card with four four-lane e-Sata port multipliers, and putting the disks in two 8-bay silent enclosures from ATech Fabrication (http://www.atechfabrication.com/products/mass_storage_8x.htm).

As much as I'd like a full Promise V-Trak solution, it's out of my budget and it's overkill for this project. I already own the Areca and 9 1TB drives. I'd like to make use of them, if possible, but I'm willing to consider scrapping the Areca for something just as fast, but easier and quieter.

Thanks for any advice.

Brad