You shouldn't be worry about it in 6b.
She's a very early bloomer, so buds that start swelling too early might be zapped by the late frosts, in such case it might (re)bloom in a fall.
It's probably the oldest of all Jap. cultivars in US.
Very distinct flowers which can't be mistaken for any other Nikko-type mopheads. Sometimes called 'Popcorn' due to succulent(ly) looking fleshy flowers.
I don't grow it myself, but know specimen that is probably 6x8' and planted next to short retaining wall along the road, so top growth is not protected in any way. I think it blooms there reliably, except extreme years, like 2004, for example, when nothing survived.
I think she'll love chosen location and you'll enjoy it for many years.

i can't comment on the cold-hardiness issue but george should know about that. mine is about 4'x4' and heading upward and outward! i think it can grow pretty big.
the flowers are unique for hydrangeas, as he describes them as having a fleshy or rubbery texture and cupped form, with a similar shape of lilac flowers. to me, the clusters are not as showy as other mopheads from a distance because of the small size of the individual florets. i am somewhat disappointed with the color of mine - it is a light, muted purple. i wish it was more vibrant. the foliage is glossy and large, though. i have it sited under a large limbed-up juniper and it grows and flowers well in the filtered light there.

I'm in Zone 7A and my Ayesha blooms about 1 year out of 3. It will need to be covered if you have any late frosts. I'm thinking of digging mine up and putting it in a big pot so I can put it under the deck during the winter.

Thanks for the responses!

I think I'll go middle of the ground and not go crazy trying to protect it, but not raking up any of the pine needles that will fall on it this autumn. I'll see how it does over the winter and into spring. If I don't get any blooms, then I'll definitely protect it next fall.

Thanks again!