I have not heard that particular Ashdown combo, but generally, 15's and 10's do tend to get along nicely together. So that is certainly a good route to investigate.
But, if you are really looking for great mids, there are a number of 12" equipped cabs delivering the goods. The Bergantino HT112, EA Wizzy 1x12 and Accugroove Tri 112 and Whappo, Jr. certainly come to mind when you think about excellent midrange. In the 2x10 department, using these same three companies as examples, the Berg HT210s, EA NL-210 and Accugroove Tri 210L have musical, full mids (and are all surprisingly light, too).
Tom.