I've got a Dell SAS 6/IR that refuses to discover, and appears to corrupt the LBA of, two 160 WD RE2 drives (WD1601ABYS). The controller works fine with every other drive I've attached on any port ...
I had the opportunity to experiment with a bunch of LSI1068E based SAS controllers. As everyone knows, a SAS controller is also fully capable of handling SATA disks. And you get a much better cable ...