It is now 2018, quite a while since Shemmelle's question. I've never posted anything, but I loved Bits of Ivory and am equally fond of Dwiggie. I've made a catalog of the stories (except for a few which I hated, like the one where a former lover of Darcy actually murders Lizzy), and can't believe how many of them there are!
As to the mysteries, I'm sure there are many.
Two series I have enjoyed are the ones by Stephanie Barron, which you mentioned - I have 10 of them, each of them allowing SB to explore various aspects of society and the position of women in those times. JA herself is the protagonist.
The second series I've liked is by Carrie Bebris, who has published 6 novels, each of which has Lizzy and Darcy as amateur detectives, interacting with (in turn) the characters from the JA novels; the first two are a bit gothic for my taste, but in general they are all enjoyable.
The other mystery I know of is Death Comes to Pemberley, by P.D. James, who has written many mysteries with her own characters. PBS made a mini-series out of it.
Happy hunting! Karin