Definitely buy local or observe local plants to see what will do well in your area. Also, there is a new feature called "Local Reports" that Dave just created for people to share growing data. It may take a while for all the cultivars to be reported on, but definitely a very useful tool!
My understanding of this concept is that each daylily has a certain genetic potential. If it's genetically a sunlight-based dormant, (dormancy triggered by shorter days in Fall) it will probably be dormant even for me here in Georgia. If it is somewhere on the semi-evergreen scale, it may have the potential to respond to temperature and/or other conditions and could react very differently in your garden compared to mine. The hybridizer typically registers a plant based on his/her local observations, so that information might not be useful to you if you live in a different zone. The choices of dormant/semi/evergreen are very general, but there are probably hundreds of variations along this scale. Hardiness, as mentioned before, is not directly related to foliage habit.
From your original question, I guess what I'm trying to say is I don't think that daylilies "develop" these traits; the traits for dormancy or hardiness are already there in the genetic make-up of the plant, but may not express themselves until they are exposed to certain environmental conditions.
