Good questions, Becky. Like everything else about daylilies, there is really no static information on performance, color stability, bud count, you name it ... and to make things more challenging, we each define the terms, and what we experience of the daylily, in our own way. So, we pool information, triangulate it against growing conditions, and find a general path to follow.
For me, there are already some I would call invasive, but the next person might be most happy to have them in their yard. I've already dug up Sings the Blues and Trahlyta, potted for now so I can get some pollen from them before I give them away. Seductor is starting to go wild on me (sigh - just as I fell in love with it) and so is Pink Flirt - my goals just don't include fast increase. I don't know that they are spreading far and wide by rhizome, but going from 2 fans to 18 in one season looks invasive to me. And, so it goes.
