Same test, but for the left side of the flipper hazards on default balloon flight which have more horizontal knockback:
1.0.3
Left held: 54 Max launch speed
No input: 56 Max launch speed
Right held: 56 Max launch speed
1.0.4
Left held: 53 Max launch speed
No input: 56 Max launch speed
Right held: 58 Max launch speed
In short: I have no idea what the **** is going on with the horizontal influence, the ability to increase and decrease vertical knockback is definitely gone though.
I just tested this and I got different results. The kb you get is probably based on holding up or down. Holding down I got 52 kb. Neutral/Left/Right I got 56 kb. It is hard to get it perfectly aligned with a direction on the 3DS pad though so this needs confirmation.
Okay so based on everything discovered until now.
-Vectoring is gone for vertical launching moves
-Such moves are only influenced by DI
-For horizontal moves (maybe Sakurai angle only?) there is DI and vectoring
-For such moves holding up increases knockback and holding down decreases knockback
-These moves are also affected by DI, which can make things confusing for survival (lower kb + lower angle vs. higher kb + higher angle)
What needs to be tested.
-What are the criteria for having this weird vectoring behavior?
-Is the degree to which kb is amplified by constant?