I commented on the 'big cursor jumps' issue, clicking is fine but it's still doing it when you edit the value now.
Acceleration can be even higher with cruise control now... new max values during calibration are 15/30, 1D/00, 24/D0
I looked at VBA and it isn't even analog? It's only up/down/left/right. It seems to not jump straight from 0 to max as you hold the key. But at the start of a level you can be holding Up already and reach the maximum value that way.
Maximum values on VBA: 76/90, 7F F0, 89/50
VBA's y speed acceleration if holding up goes
00 00, FF 78, FE F0, FE D4, FE B8, FE 9C, FE 80, FE 64, FE 48, FE 2C, FE 10, FE 08
In BizHawk, this acceleration matches 90 cruise control + -10 tilt, so VBA's "up" would probably match 100 tilt in BizHawk?
Oddly, despite a faster initial couple frames, VBA's -100 comes out slower than BizHawk's -90 in reaching top speed of FE 08:
00 00, FF 88, FF 10, FE 98, FE 80, FE 68, FE 50, FE 38, FE 20, FE 08
And BizHawk's -180:
00 00, FF 08, FE 10, FE 08
Is faster than VBA's -200:
00 00, FE D8, FE 94, FE 50, FE 0C, FE 08
FFF3 = adjusted X?
FFF5 = adjusted Y?
FFF7 = X calibration
FFF9 = Y calibration
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This has been a lot of information to try to wrap my head around, so I've put together another comparison just looking at Kirby's position shortly after starting a level after reaching max speed. Due to annoying framerate differences I decided to sync these screenshots by looking at the "200" in the corner and syncing it at a certain position. That should be consistent across all 3.
https://imgur.com/a/LEfs6Bc
To me this shows a clear win for the Gamecube, so perhaps the goal should be to reach that (approximately) "29/B0, 38/00, 45/70" range of motion, which is larger than Biz or VBA. (By the way, where does the initial main number (1D in Biz, 38 on my cart, ~80 on VBA) for that byte pair come from in the Bizhawk code?)
My hope is that by the end of all this, we aren't stuck at a huge cruise control the entire game...