A dedicated midrange is a great thing to have, however if you decide to go that route, I recomend you do a few things, dampen the hell out of your door panels, and then when you think you are done dampen some more.
If you feel obliged to use factory locations, you may want to get an additional tweet and place it on the a-pillars, to raise the hieght of your soundstage. Wiring the mid on the oppisite out of phase should help a bit with imaging locations.
Currently I have a cdt audio 642 setup, and the accuracy of these drivers is phenomenal. Mounted in stock locations in an e36 coupe.
I would advice to stay away from a/d/s they have had financial difficulties over the past few years and not have created and decent products. Directed has bought them out and probably intends to bank on a good name of the past.
THere are many newer companies that are attempting to make a name for themselves and have a great product also.
Feel free to hit some audio dedicated sites if you want to go at this indepth,
www.elitecaraudio.com is my favorite board when it comes to that.
Nes