Yeah. I have an Adaptec AAA-133U2 card with 16MB of cache and four 9.1GB LVD drives in RAID 5 (27GB usable). The card is a three-channel LVD card which means you can get a possible throughput of 80MB/sec on each channel. By putting at least one drive in the array on each channel, you get an aggrigate throughput of 240MB/sec.
All I know is that with the 16MB cache, combined with 10k rpm drives, this damn rig SCREAMS and load times drop through the floor.
At work I also work with Compaq and Dell servers, all of which have SCSI RAID 5 setups. I wouldn't put anything less into a server these days (unless it's just a web appliance or some other tiny box).
To quote Ferris Bueller: "If you have the means, I highly recommend it. It's soooo choice."