I think woody has it spot on....much as I do too.
I keep many dahlias in the ground but also dig up varieties to pot up. Been doing this for past couple of weeks. I use 5 litre pots or smaller if I can easily pull apart. I will label instead of guessing too this year. If I have forgotten the variety name I write a brief description of it.
I too dont think frosting improves anything as long as tubers get a chance to dry off before any cold weather arrives. Fatal to dig up in cold weather and hope they will dry out in the GH .....should anyone ever actually do that !
I once said dahlias aren't my favourite plants but I've come to enjoy them more this past year or so.....maybe sInce my visit to national dahlia collection not too far from me....and I have several varieties now. The singles ....simple, subtle and charming...(bit like me ) .are now my favourite.