For those following the ongoing saga, I got my Oktagon 2008. Turns out it's a rev. 7 with 6.12 ROM so that's nice. Setup was super easy. The install floppy is available online and my new Gotek came in handy to get it going. Actually, the machine reported the card as defective when I first plgged it in, but I cleaned the edge connector with my Mars Staedtler acid-free plastic eraser, wiped them off with Deoxit Gold and reseated the ROM. Then it worked fine. It's not the fastest controller out there but it has one big advantage over my A2091 - it works.
The only problem I have now is that I can't get a SCSI2SD device larger than 1 GB. I've set a 4 GB size for the first device in scsi2hd-util on the PC and the Oktagon installer reports its size as 4 GB but when I open the new disk in Workbench, it says it's only 1 GB. This is WB 1.3 though so maybe that's it. I'll try upgrading to 3.1, which I need to do anyway to get my Deneb running.
So then I'm thinking - it would be nice if I could figure out what's wrong with my 2091. I powered it up on my bench and found that diode D1 was open, so I replaced that. Then I found that U7, a 7407 hex inverter was turning up squirrely numbers so I'm going to replace that too. I have a lot of IC's in my stash, but not that one. So I'm waiting for that now. There's a video on Youtube (
https://www.youtube.com/watch?v=swU3w6_ipLs) that describes my problem almost exactly.