I saw a diagram somewhere of how these guys are supposed to look - looking at them straight on - and it's like an upside down rounded triangle. I think it was in the book "Feather Brain" by Drew Chicone. Critical to get them to run right. Fantastic book by the way.
Personally after fishing a Zoom Fluke for bass for many years(my goto lure in the tournament scene for certain lakes), I don't think it matters if it darts upside down, or what. It's the side to side erratic action that drives the bass crazy(you would be amazed the action I could impart in a fluke, I twitch mine harder than most people and slay the bass..I really like to get it to spin 180 degrees and look at the bass in the face....oh it's ON THEN!)....sometimes when they aren't active it's more less "dead sticking it" and fishing it like a senko.
I would assume the Gamechanger is the same, since it's basically a Fluke/Swimbait Style bait.
Now Swimbaits are fished with a steady retrieve, you don't want the bait flipping, darting, ect...never stop reeling was always the "lesson" with conventional fishing and swimbaits. BUT that is a specific deal, timing, location, water clarity, ect.
Flukes work in a wider variety of conditions. That is how I fish the Gamechanger (since we really can't have a constant retrieve fly fishing).
Food for thought!
Bass are like House Cats!!
Side Note - I built a test tank and tested mine, they look good. One thing I notice on the Gamechanger Chenille, is if you sparsely use the material the fly will have more action and sink faster, more material slows the action and slows the fall. You would want the slower moving, slow sinking one in winter when its cold, erratic one during the warmer mouths.