AEK were built with Alps SKCM Orange and Salmon switches.
AEKIIs were built with...
Alps SKCM Cream Damped
Alps SKCM Salmon
Alps SKCM White Damped
Mitsumi standard mechanical (linear)
It's almost the same, but height adjustable. Note that AEKs / IIs came with different switches, so they're not all the same as each other. I prefer the AEKII :p
There is also the possibility of using external power for the bus, so you can power more devices, but you'll need to not put too much current through any of the devices.
The extreme would be putting an ADB hub with external power every 5 devices :)
We struggle a bit with BlueSCSIs, generally it is worth going straight to the seller's support as it is a current product, but also they keep changing things.
@LaPorta - it's not used much at all. You'd never use it unless you were doing calligraphy or other heavily stylised text, or writing a certain type of fiction. The only usage I remember off the top of my head is dæmon, which isn't how normal people spell it. The internet tells me it is called...
So just checking things.
The "MIDI Manager" software has several parts.
MIDI Manager - this can go in the System Folder or Extensions folder.
Apple MIDI Driver - this must go in the System Folder
PatchBay - this is available as a DA and an Application. I just use the Application and put it in...
I think 2.0.2 is the newest. It is a very old bit of software that predates System 7 and your Duo.
Does this help? I've not used it :
https://macintoshgarden.org/apps/midi-mangler