Mmaaaaaaaac....
I really can't reproduce your numbers. However, you're right that this "egg braking" (the G&W ppl call it "bucket braking" now, lol), doesn't really help all that much. At least not on small/medium sized stages, anyway. It helps the most on long-distance KOs, particularly on big stages; the amount of improvement you'll get, and indeed the recovery method you should use, is really dependent on the distance you're going to travel and proximity to both the side and ceiling killzones.
I don't know why you say you should airdodge; Yoshi's fastest aerial is his Uair (not his Bair; I've found a situation where I can
only survive with his Uair not not his Bair, lol), and surely the Uair is faster than Yoshi's airdodge... maybe by about 10 frames? Just a guess. And you can fastfall an aerial whereas you can't fastfall an airdodge, so using an aerial should be strictly better than ever using an airdodge, as a method of cancelling hitstun so you can avoid the killzones.
Now, I'm also unable to reproduce the effect you describe using Yoshi's B-reversed / wavebounced / reverse B-sticked / whatever you want to call it, up-B. I've noticed that if you're in knockback (after you've escaped hitstun), using Yoshi's up-B causes an extra boost away from the stage. Furthermore, I get the same effect no matter how I perform the up-B, I wasn't able to get any sort of momentum-change from B-sticking it
while I'm in knockback. Is there something I'm missing? Are you sure you were performing it during knockback? I recommend testing on a large custom stage so that you can see Yoshi clearly during the entirety of his knockback trajectory.
Anyway, I just spent a long time experimenting with Yoshi on FD, since I couldn't reproduce your numbers... here are MY numbers
They illustrate some interesting things... man, recovering with Yoshi is tricky.
This is in training mode on Final Destination. I'm using the back side of MK's Dsmash, which hits for 13 damage. MK is always positioned to the left of Yoshi, hitting him to the right. The numbers indicate the lowest damage I can give to Yoshi where he will die; that is, I can get him to survive at any lower percent, using the specified recovery method.
Yoshi's teetering at the right edge of FD:
No input: 77
Leaning towards the stage (after hitstun starts; no DI): 83
Bair > Jump: 84
Uair > Jump: 85 (Uair is faster than Bair)
DI up + lean towards the stage: 105
DI up + Uair > Jump: 113
Anything involving side-B is death; since we're too far horizontally, and not high enough vertically.
Since we were dying off the side, it doesn't matter if we fastfall the Uair or not.
Yoshi's at the very centre of FD:
No input: 117
Leaning towards the stage (no DI): 125
Uair > Jump: 135
side-B is death, with no DI.
DI up + lean towards the stage: 153
DI up + Uair > Jump: 152 (yes, this is worse! Since the jump would kill us off the top)
DI up + fastfall Uair > Jump: 159 (we're at the corner, but die from the side killzone)
DI up + fastfall Uair > Jump > side-B: 160
So there's our first example where we needed to Jump to avoid the side, but needed to cancel the Jump with a side-B so we avoid the ceiling.
DI up + Uair > side-B: 157 (we're in the corner, but seem to die from the ceiling at 157% or higher)
DI up + fastfall Uair > side-B: 166
In that last option, at any higher % we could still survive the hit, but be too far sideways to grab the ledge as we return to the stage. Note, I'm cancelling the side-B as soon as I can, since we have more mobility in the falling state afterwards, than during the egg's drop.
It's quite possible that there's an optimal way to DI that Dsmash, where we can use a better combination of fastfalled Uair > Jump > side-B that would survive at or beyond 166%.
MK teeters at the left edge of FD:
No input: 146
Leaning towards the stage: 155
Uair > Jump: 169 (at the corner, looks like we die off the ceiling)
FF Uair > Jump: 169 (same result, but it looks like we die off the side now, lol)
side-B is death, without DI.
Uair > Jump > side-B before we hit the ceiling: 175
fastfall Uair > Jump > side-B before we hit the ceiling: 174 or worse.
In that case, there's a VERY delicate tradeoff. We want to fastfall the Uair, which gives us more vertical space, so we can spend more time jumping. The only purpose of the jump, though, is to gain us as much height as possible, before we start the side-B; so that the side-B can be cancelled early enough, that our drift towards the stage will allow us to grab the ledge. However, we're still flying away horizontally during the Jump; Yoshi's Jump isn't very effective at counteracting knockback.... I mean, it fights knockback, but we're still travelling away from the stage throughout almost the entirety of the jump; we're just flying towards the side
slower than if we hadn't jumped. Anyway, fastfalling the Uair is basically undoing the point of using the Jump itself, which is to gain us height. This is why it was slightly better not to fastfall the Uair, and use the side-B quite quickly after the Jump.
God that was complicated
Finally,
Di up + fastfall Uair > side-B: 168 (this is bad now, since DI'ing straight up sends us over the top.)
From the left side of FD heading right, MK's Dsmash sends us at almost directly towards the stage corner; so that's about as good a "long distance KO" as we'll find on FD, with which to experiment with these recovery tactics.
Still, you'll see the relative gain from using side-B as a recovery measure increase a lot on larger stages, especially with walk-off edges.