Thanks for the replies.
I'm still pulling my hair out with this one, but I think I can safely conclude it is not the driver that's the problem, but seemingly a kernel bug. I found that booting into the older Wheezy stable kernel (3.2) is fine with these cards, but the 3.16 from Jessie is not. Even booting the live CD into Jessie proper does not work with the cards.
I did find a 332T lying around, and that seems to work without issue at the moment. Might just ditch the Intel-based cards so I can get this up and running.
