Sounds like you are already on the right track, courtesy Peter Hansteen, so I'll simply support the direction you are going by telling you that I back up my systems (with a home-brew scheme that uses a combination of rsync and tar) to 7200 rpm SATA drives in USB shoeboxes with ext2 filesystems and have done so for years running Linux and for the last 10 months or so running OpenBSD on the same set of hardware (an assortment of Thinkpads, a Lenovo workstation, and a cheap HP desktop). I've had no performance problems with OpenBSD doing backups to these drives and therefore I haven't any measurements to quote. But I'd notice it if OpenBSD were a factor of 5 slower; it isn't.
/Don Allen
