With 24 drives it'll probably be the controller that is the limiting factor of bandwidth. Our HP SAN controller with 28 15K drives delivers 170MB/s at maximum with raid 0 and about 155MB/s with raid 1+0.
I get about 150-200 MB/s on .... a linux software RAID of 3 cheap Samsung SATA 1TB drives (which is my home multimedia server)... IOPS would be of course horrendous, that's RAID-5, but that's not the point here.
For raw sequential throughput, dumb drives with dumb software raid can be pretty fast, IF each drive has a dedicated channel (SATA ensures this) and the controller is on a fast PCIexpress (in my case, chipset SATA controller).
I don't suggest you use software RAID with cheap consumer drives, just that any expensive setup that doesn't deliver MUCH more performance that is useful to you (ie in your case sequential IO) maybe isn't worth the extra price... There are many bottlenecks...
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