It did fine for me last year at under 600 hours. I would keep it you will know in exactly one year if it will work. Its the best erect thornless blackberry I have.

Look into a product called "Dormex". If you decide not to keep it don't throw it away, give it to a friend in an area with more chill hours.

I don't know how they taste, but Choctaw only needs about 300 hours; Kiowa only about 200 hours.

Perhaps the more important question is whether you want to wait 16-17 months (fruits on 2nd year canes) to find out if you are right. If you are wrong, you'll wait another 16-17 months after choosing a variety that is better suited to your environment. If I were in your situation, I'd just chalk the $30 Berries Unlimited purchase up as a learning experience and purchase a low-chill variety.

Fruits for me in San Jose, which is 400-500 hours chill

$30? Is that for a 5 gallon plant?

Fruitnut does quite well growing brambles in pots. Maybe you have room to try several different ones in pots?

He keeps the canes wrapped in a circle so the whole thing is rather compact.

Finally - Boysenberry. I don't know what the chill requirements are but there used to be thousands of acres of them in SoCal. And they survive my San Joaquin Valley summer heat (90s to 100+)