Cuttings are the usual way to grow in England. Tubers are dug and stored whole, then "woken up" in Jan, cuttings are taken as the sprouts emerge, and once the sprouts are established plants, the tubers are composted. When ordering dahlias - they ship cuttings, pretty much never tubers like we do.
If you are growing multiples of the same plant then it makes total sense, you get a lot more.
Glad you are having success with it.
