I recently got my hands on an Adaptoid (these things are EXPENSIVE these days :x) so now I can use it with this plugin.
I don't think it will ever support the Transfer Pak, right now when I stick the thing into a controller it says it's a blank mempak. Unless someone can improve the source code for the Adaptoid drivers, I doubt the Transfer Pak will ever work properly...
Another thing I've noticed: Whenever I use "Direct rumble" with the Adaptoid, and click "Test Rumble" the emulator will close completely (crash), but it still works in the game. Sometimes it won't work at all though, on any rumble setting, but that's probably an Adaptoid driver problem and not a problem with the plugin. Reinstalling the Adaptoid drivers seemed to fix that.
Using the "Adaptoid Pak" option just lagged the emulator enough to be really annoying. I remember seeing something on the front page of this thread saying "Rewrite Adaptoid code to be asynchronous," is that what this is?