Has anyone had luck planting these in the ground? Do they need winter protection? Thanks!

I have kala heera which is close to it. I find first year in ground was pretty slow grower. This year and a faster start growing still no fruit. As far as protection i live in Louisiana so no protection in winter. You get snow so i would protect it for a few years till its established. Richie
LOUISIANA
9B

Remembering that your breba buds are overwintering on your trees and that temperatures under 28 may harm brebas and under 17F will kill them I wouldn't put a DK in the ground when you might experience 0F or 10 F for long periods.

DKs are by far the most productive figs in ground here in 7B Seattle

Here in MD zone 7a last winter I have several in-ground figs (Adriatic JH, Mt. Etnas, Filacciano Bianco) that had viable brebas survive the winter without protection.  It got down to +7 degrees one night and down to the low teens on about 3 occasions.  Unfortunately, I lost all the brebas from the Adriatic JH because after it came out of dormancy (with brebas starting to swell) and we had a low of around 26 degrees and couple other nights around 28 in early April.  That tree still hasn't hardly broken bud at all.  Other figs that were still semi dormant in early April are now starting to leaf out.

So to answer your question, I would guess that most years your DK would produce fruit without protection but occasionally you would lose the brebas due to the cold.

My DK in zone 6a has some brebas starting. I had it wrapped with carpet and stuffed with dry leaves though to get it through the winter.