I've tossed around the same idea, knightly orders from Middenheim. The general idea is that on horse would be all White Wolf and Kinghts Panter, and using the Tutogen (sp?) models as greatsword-equivalent White Wolf on foot. I currently don't have enough White Wolf knights yet, and am only now looking for great-hammer wielding foot troops.
I've not read the newest Empire book to see if the lore and background of these orders have changed but older editions of the Empire army book and also the original WFRP had both Knights Panther and Knights of the White Wolf based entirely out of Middenheim, with a semi-friendly rivalry between these 2 orders.