I don't see a problem with winter tyres, there's Michelin Pilot Alpin PA4 in both 255/40 and 275/40 R19. I'll get another set of wheels for these winter tyres.
There's also Nokian WR Snowproof P, Goodyear UltraGrip Performance+ or Pirelli SottoZero III in both sizes so plenty to choose from.
305/30 or 315/30 R19 don't exist for winter tyres here and I wouldn't want to run those widths on those great looking HP wheels in winter anyway, best to get a separate set of wheels with regular tyre sizes for winter.
I would never recommend all-season tyres to anyone, they're mediocre for summer and not great for winter either (but that depends on the kind of winter you have, no snow or ice like in Florida could be fine for all-season).
This is high performance car and it deserves high performance tyres, best for the best
Like you said there are some good choices with winter tires in both sizes 255/40/19 and 275/40/19.
I live in region of Germany where winter is usually mild so good all-season tires work for me however, best choice might prove to be the winter tires as you suggest.