Interesting. I would love to have a C. 'Venus", but it is a hybrid, not the species or even a cultivar. I do have one C. spp.

Yes, good info there, thanks for posting. I remember seeing Venus available at a couple local retailers several years ago, but haven't seen it locally since. One online reference recorded heavy dieback on Venus after -20F, so it may be a bit less hardy than the others. I think it's notable that Aphrodite managed to get a 4-star rating even though the article describes it as a "bruiser", and a "behemoth", and "occasionally appear[ing] a little unruly or unbalanced because of long, vigorous stems". The relatively young plants (Aphrodite) I've seen in the area are attractive and do appear to be relatively vigorous. Burgundy Spice and Dark Secret must have been too new to be rated in the trial yet. Sounds like they may turn out to be more compact than some of the other selections.