I use a similar alg to Chris's to flip two adjacent edges. For other cases:
L E L' B2 L E' L' B2 E B2 E' B2 flips FR and BL
B2 L E L' B2 L E' L' B2 E B2 E' flips FR and BR
Both are just two 3-cycles merged together, none of these 3-cycle is center-safe but their effects on centers happen to cancel
That's a very cool way to handle those cases!
To flip more than two midges at once, I've found nothing better than (MU)^20 (for 4 midges)) for the moment.
Wow, I like that a lot! If I'm not mistaken, that's supercube safe.
This analysis uses my blindfold lettering scheme, as I am at work and need to make this post brief. If anyone wants me to, I can translate it into Speffz. I also did (M' U)20 instead of (MU)20
t-centers: (APXECDMUHB) 10-cycle identity
x-centers: (ABDC) 4 cycle identity
wings: (QNJE)(IFRM) two 4-cycle identities for an overall 4 cycle identity
corners: (ABDC) 4 cycle identity
midges: (APXQ-flip)(CD-flip) 8 cycle identity with a 4 cycle identity, an overall 8 cycle identity. Every 4 cycles will flip the midges at UL, UB, DF, DB and return the UR and UF midges to solved.
Performing (M' U)20 will perform an identity on all pieces types, except for midges where it will leave UB, UL, DF, and DB flipped.
I imagine you already knew this, but I wanted to write this in case others, like myself, were wondering about if this alg was supercube safe. I may actually switch to this - I'll have to try it in a solve and see how it goes. Very cool, thanks for posting this!