I've heard of some people not liking Chester, but this is a mystery to me as my family loves home-grown Chesters. Maybe it's because blackberries aren't grown around here so I'm comparing store-bought berries with homegrown, but at any rate I really like Chester. And it is hardy... I'm in zone 3 and have to cover them with leaves and burlap to survive the winter, but they do survive and produce fruit.

I lost about 50% of my triple crown *TC's) floricanes this year but I'm still getting a reasonably good harvest from them. The hardiness zone rating provides a 'general' guideline for growing fruits and vegetables. The actual location of your planting may also impact your plant's cold weather hardiness. Exposed locations that get a lot of wind will increase the likelihood of cold injury whereas protected locations may help reduce cold injury.

My TC's were in the most exposed location in my berry patch, and they took a beating when temperature fell to below -5F five times (-7F max) and we had sustained 20mph winds. My Ouachita's are in a more protected spot and didn't get much injury from cold.

My parents grow Chester blackberries and they are highly productive. The flavor is mildly tart but fine for eating fresh or for cooking. Ouachita is only marginally better in flavor but less productive. The other plus for Ouachita is that they are easy to manage because they are erect plants that need little trellis support. Chester and triple crown are both very large plants that need a robust support structure. I think Triple crown has the best taste of the three and probably the best taste among all of the other eastern varieties that I have tasted.

Yeah both my triple crown and chester lost all canes this year. I need to protect them. I was thiking besides covering them to try an anti-dessicant spray.
I harvested my first boysenberry (wow, these were super flavorful, and slightly tart). and my first tayberry. Only a dozen will form, destined for jam, I didn't taste it. Oh I got a wyeberry too, the thing was huge! I should get a couple dozen. Next year I will get loads of berries.

When I lived in Ohio, my neighbor had some Chesters.

He got a "full" crop about 3 years in 5, a small crop the other two years, and told me he lost the entire crop in '94 but no other time. However the crowns always surivived and sent new canes.

At least with brambles - even if the floricanes die, you usually don't lose the crown - and unless another severe winter hits you get a crop the next season...whereas a tree like a peach, if the wood is dead, the whole thing is dead and you "start over" so to speak and lose a few years before your new tree fruits.

I wonder if you could increase your success by planting a screen of a tall, narrow conifer, like arborvitae, on the north and west of your planting area to keep the wind down, but far enough back that it doesn't shade too much.

Or even if you're not protecting them with mulch and all, I'd think even just throwing some burlap over the canes might keep the drying wind down a bit.

Just a few random ideas.

My chester lost all floricanes, but as you mention the crown survived. I expect more severe winters, so I'm protecting them next time. I had one peach tree lose most of it's wood, but it was not dead. Some above the graft was OK, and so I didn't lose the tree. My other three peach trees only lost fruit buds, no damage to the wood.
And a note, the crown of my loganberry did die, and Navaho was hit so hard the crown didn't produce till mid summer. I thought it was dead. I have 3 inch canes now, rather small for the middle of July. Glad it's alive at least, huge setback though.

I have triple crown and chester growing right next to each other on the same trellis. This past winter we got down to at least -10 my neighbors claims -12 and the tripple crown died down to about 2 ft above the soil line. This is it's second year in ground and it still is producing a lot of fruit for what is left. The chester did just fine with the winter and is over 10 ft tall right now sending out tons of laterals on the primocanes so next year should be really good for berries. I can't tell you how they compare taste wise as only my triple crown has given me fruit so far that were very good.

My Quachita in z5 Omaha Ne area lost all canes this year for the first time since planting in 2009. It normally has the ends die once they get down to a tiny diameter.

FYI - I think Gurney's sells a primocane black raspberry, but calls it something else - might still be the same one as the Niwot the OP mentioned. I'll search for it.

I saw it this spring and was intrigued.

FYI - "I think Gurney's sells a primocane black raspberry"

Yes, I think Henry Fields, and yes it is Niwot. As you say named Sweet Repeat, but if you look at the details, the cultivar name is listed. Nourse sells Niwot now, probably next season. Tyler called them and got some this year.
Mine is doing well, thowing out a couple primocanes.
You know Gurney's and Henry Fields are decent nurseries for how large they are. Some things are expensive but they have sales all the time, and it's possible to get great deals. I bought a Carmine Jewell for 7 bucks, and it was a really nice plant.
Everything from them has been nice.

Both my chester and TC had cane loss, though I think the TC had it a bit worse. Both are still looking like they'll give me a good harvest if I can keep SWD away from the berries. I've liked both Chester and TC for taste.