1:
>blind spots for first four edges
>z2 rotations
Both not a problem with M-slice edge pairing!
Also, it's true that first four edges are less efficient with redux versus Yau, but that's made up for by centre efficiency. (For centres, redux wins slightly for 555, and it wins a lot on 666+ because you get rid of lots of crappy slice moves that are "unavoidable" with Yau.)
2:
You can do L4E in redux with no blind spots by shifting the edges to FL/FR/UF/UR first. This takes like five moves or something and it's essentially identical between Yau and redux (for E-slice edge pairing); Yau5 is the oddball where you solve two F2L pairs first. Yau5 seems to have fallen out of favour because transitioning from edge pairing to solving F2L pairs, and then transitioning back to edge pairing is bad for lookahead or something. (I'm not up to date on the Yau meta.)
3:
Yeah, the 333 transition sucks for redux, but (IMO) this is similar to hunting for cross pieces while solving the cross in Yau, and you have to do this three times as much in Yau compared to redux!
Anyway, your points are valid; I just think that Yau doesn't "truly" get rid of the flaws in the redux method, but instead shifts them to different steps. I personally use redux just because I'm not CN (redux gives me six choices of centre to start with, Yau gives me only two) and I don't like having to keep the cross intact while solving centres.
