Not sure, but I think I may either have royal purple or just a 'generic' one, and it seems to behave in the same way mentioned above. Mine's on the southwest corner against the house. I like that it dies back as if probably means the foliage will be bold and colorful each spring plus it's a neat as a dieback perennial.

You can grow a lot of things a zone or 2 north of where they're rated as dieback perennials. I've got crepe myrtles here in Michigan that do that. They virtually never bloom, usually have just buds when the October freezes zap them, but the foliage is glossy and pretty.

I admire smokebushes in the area all the time, although I don't have one of my own. They certainly aren't dying back. No idea what type they are. Winters here can be quite harsh. (Northern edge of Southern Ontario...Zone 4 plants do not overwinter here.)

Mine dies back each year, but this year, for the first time ever, I got flowers. Thank heavens for the monsoons.