I would argue, however, for spring. I found that my Montrose Ruby tended to heave out of the ground when it froze when I divided it in the fall, however a friend that had grown them in this area for years said do the job in the spring allowing for the plant to get its roots down more firmly and deeper over the growing season...
Lotsa varieties (we call them Coral Bells here in the western U.S.) but we also like the lighter shaded Peach Melba (among about 5 or 6 others).
Good luck!