They're beautiful. After seeing your post, I consulted the new Darke book, and he has quite a few nice things to say about them. He lists and pictures several cultivars in each sub-species.

They'll have to go on the list.

Darke says they're cool season grasses, but Bluestem says warm season.

Which is it?

Not many of the growers seem to offer them. Kurt Bluemel has quite a few, but others have none.

I have Skyracer, Windspiel, and Transparent and love them all. Skyracer is my favorite OG. I have it at the front of one of my borders, and when it flowers it's just incredible, waving in the wind. Lets hear it for the Molinias!

Donn,
From a digging & dividing point of view I would definitely class them as warm season grasses. I don't get any new growth from them in the fall after they have flowered. That would be one of the criteria ..... They do start growing a little earlier than some of the other warm season grasses - maybe that is where they come up with the different classification?

Of the tall ones (ssp. arundinacea), I'm growing Skyracer, Windspeil, Karl Foerster. I also have Heidebraut, Moorhexe & Variegata. Love them all!
A.

Had Windspiel here. Ab glorious grass with one big exception. It cant right itself after a big rain & here we have those fall deluges which turned those divine fountains into sodden mats. So out it went.

I must admit that the Molinias are more of a 'enjoy them in the growing season' kind of grass. Some years mine are good thru most of the winter but, often they get knocked over by an early wet snow & then that's it.
However, they do bloom a little earlier than most of the warm season grasses & while they are good, they are glorious.
A.