Yeah, I've noticed this as well. I pretty much view the SCSI2SD as useful in a 'special' machine - in my case, the LC III. However, as wonderful as it is, it's a bit costly (in relative terms depending on a person's disposable income, or the level of their spouse's understanding) to outfit one's entire collection with SCSI2SDs. I've pretty much replaced all of my Macs' hard drives with 2.5" 10k SCA drives. I mistakenly bought a couple 3.5" SCA drives, which I was worried wouldn't fit once the adapters were on, but in Macs like the LC 630 and 7100, they've been fine. All that said, I'm thinking about getting a second SCSI2SD to act as an external hard drive that I can boot from to install systems and transfer applications over from.
That adapter gets part the way there, but not fully - it needs termination. Max1zzz is worth talking to if you're interested in figuring out how to modify that board or, indeed, buy a couple boards straight from him that simply do what they need to (that's what I've done).
