(I might be slow on the uptake)
Well, yeah, you are a bit.
This is really nothing new and was widely known even when the A2091 was new. The A2091 is about identical to the A590, which has everything installed to use XT IDE drives. In fact, most (if not all) A590s had XT IDE drives installed.
Does it work with the IDE to Compact Flash adapters?
No. It doesn't work with anything else than XT IDE drives, which means you can't use anything else besides a few 20-80 MB drives from the early 90-ies or late 80-ies. XT IDE was almost non existant back then (and rightly so), so finding a replacement drive would be next to impossible nowadays.
What you hope it to be is an AT IDE controller, which it is not. So, yes, it is easy to make the XT IDE connection fully operational on your A2091 and yes, it is completely useless.
In theory, you can design an adapter, making it possible to connect AT IDE-drives to an XT IDE controller. That would require you to build an AT controller with a built in adapter and connect it to the XT controller of the A2091. Which kind of defeats the purpose, because it would be much faster, easier and cheaper to just put an AT IDE controller on a Zorro card, which would make it a
Buddha.
