Johan,

> The system has 4 x SATA disks and I'm looking at either
>
> * Adaptec 2410SA (supported by aac(4))

We have that one running in a number of machines, from a box still running
NetBSD 2.0.2 to a few boxen on 3.1, including two machines running
Xen. They Just Work, have a decent Bios to configure most things from and
we haven't had any serious problems in changing disks with them.  They can
even reconstruct their RAID set whilst you're already running the system --
this just leads to a disk performance decrease, but not machine downtime.

I don't have first hand experience with the 3ware SATA cards, but I'd just
by the Adaptecs again because we haven't been burned by them.

Konrad