Simon, in that first video it sounds like they're surging (not shuffle but surge). It could be just the video though.
I have just done an overlay between your graph and mine. Obviously its a little rough but I was going up in 250 RPM points.At 4500 RPM we are the same, you overtake by a rough average of 20-30 kw then fall away at around 6300 RPM. Different dyno's and whatnot so it isn't the most accurate thing.
Now, if you went from 550 WHP to 632 WHP (on this sheet you posted) and nothing else changed, then that is farken silly. Can you remember what boost level the -5's were running to achieve that?
I spoke to the guy that tunes my car and he said to go the 63's. Now considering the -5's are a 360 HP turbo, 60's are a 400 HP turbo and the 63's are a 430 HP turbo, I'm not sure if I need the 63's. The 60's should (on my engine seeing that the -5's have already done 472 rwkw) do 500 with a much better curve to match (as you have not given away anything at any point), couple that with a 250 degree at 11 ish mm lift and it would be silly. What I am really curious about is that throttle response/lag between gears. It doesn't exist!
Also, Gav from WA went from -5's to 63 mm GTX's and the last time I spoke to him, he was going to go the 67's. I wonder where our little rear housing is going put the white flag up and call enough?