What makes you a geek?

[Concillian]

And actually U320 is still faster than 3 GHz SAS, not slower, at least with a single drive. U320 is 2560 Mbits/sec, 3 GHz SAS is only 2400 Mbits/sec. Albeit the bandwidth of U320 is shared among all the drives on the bus.

Speed of interfaces is largely irrelevant when the internal transfer rate of the drives is well under half the theoretical max of the interface. There are only two times transfer rate of the interface matters:
1) the data is stored in the hard drive's cache (very rare)
2) you are using a solid state drive (very expensive)

I used to use 15k RPM SCSI drives (I ended up getting them free, just had to buy the controller... I work for a manufacturer) But SCSI / SAS for home users is pretty much dead now. The storage geek home of the now and future is:
1) large network attached storage (multiple SATA, mirroring for reliability) for large files (video, music, etc..)
- It's cheaper to get 3 SATA drives and mirror them than a single comparably sized SAS drive plus controller. Reliability of SAS > SATA, however, reliability of 3 mirrored SATA > SAS.
- These types of files are largely not speed sensitive in a home environment, so speed benefits of SAS are minimal.
- Also serve as backup location for client machines (mom, dad, and kids' computers)

2) local drives, if you want fast, will be solid state drives. With large files on the NAS, the client machines can have relatively small HDs and the latency advantages of solid state drives far outweighs the advantages of SAS drives. These can be run on SATA, so you can appropriate budget from a SAS controller to the additional cost of the solid state drive.

Just my opinion.

And yeah, some of that is why I'm a geek. Some of it is the D&D1 books I have tucked away, and some of it is that I build and test my own home speakers.