So I can do a real apples-to-apples comparison, I'm dumping an image of the original hard drive to load onto the SCSI emulators. I've determined that the fastest way is to pipe dd to ssh with no compression. I'm getting about 4.5Mbps while doing this, not too bad really. I had to temporarily reconfigure sshd on my home server to allow old ciphers and key exchange algorithms, but it's still pretty amazing this IRIX 6.5 system has an ssh that can talk to a modern sshd.