I did a honeyberry taste test with two other people today and here's what I came up with. Some plants are three years old, some are four. I didn't try to protect them from birds. What you see is the yield of each plant. I should also add that we've had an exceptionally rainy spring, so that probably had an effect on flavor.
Tundra: Probably the most blueberry like in taste. Good tart/sweet balance. Enjoyed by all.
Cinderella: Good sweet flavor with a pleasantly sour aftertaste, which maybe came from the skin. This was my second favorite.
Borealis: Tart and a little bitter. Plus this one was hard to pick as the berries really clung to the plants. I'll give it one more year but probably remove it.
Indigo Gem: Sweet and somewhat sour. Similar to Tundra. Also enjoyed by all.
Blue Velvet. Small yield. Tart/bitter taste. I'll give it one more year.
? is Aurora: Easily the best of the bunch. Sweet flavor, good chewy texture, and best size berry and yield. A clear winner.
All in all, I'm a fan of these fruits. I can see how in a few more generations of breeding improvement these could become a very good garden berry that competes with blueberries.
Kind of an odd side note, there were quite a few berries that had this strand two-in-one look. Not sure what that's all about.