The Jewel black-caps are thorny--not like roses, but enough to fishhook children (and me). The flavor is more akin to black currant than to blackberry. You must let them ripen to dull black else they will not pull off of the stem. They ripen earlier than most blackberries. Much seedier in the mouth than blackberries.

Black Satin is listed by some as zone 4. Must be dead ripe else will pucker mouths, including Peter Rabbit's!

I am zone 5, some winters a solid zone 4..I grow Arapaho and Navajo.....they are both thornless, and very hardy here.They do come in earlier, but that's about all I can say for them. I have both thorned and thornless, and from what I grow, you seem to give up flavor when you give up thorns! I think that well trellised blackberries are easy enough to pick, and the thorns aren't that much of a problem...if I didn't already have thornless established, I wouldn't grow them...they just aren't that great.
I picked tons of wild blackberries as a kid and the thorns were just part ofthe experience...kids adapt and learn! My kids always picked thorned fruit, and they lived! Donna

Black Satin sounds a little tart. As for the taste, has anyone tried Loch Ness? I've read they're supposed to be sweeter and do well to zone 5.

My first choice is purple raspberry...don't care about the thorns if they're purple (LOL) Seriously, thorns are okay, as long as they're not the kind that grab you and pull you in as you walk by :)

I haven't had any luck with Chickasaw a thorny variety in Z5. I'd be skeptical of thornless in Z4.

They finally just came up with two THORNY varieties of blackberries that will survive in zone 4: Prime Jim and Prime Jan. So there's hope something thornless might appear in another 5-10 years. (I can hope, can't I?) Meanwhile you could plant one of those two and trellis it, so it's easier to pick, since you are putting it at the back of the garden.