rats,
Flap 20 is not the "recomended" s/e landing flap on the 777- at least not by Boeing or the Carrier I work for (who happens to operate more 777s than anyone else).
It is optional flap 20 or 30. You can use flap 30 provided you can make the approach climb gradient. Are you saying the Eng Fail C/L prohibits flap 30 if over MLW, as mine most assuredly doesn't. Which operator are you with?
There has been a cultural bias towards using flap 20 in the Sim, but this has been recognised as negative training and is being changed.
You are unlikely to have any performance problems Flap 30 s/e in a return to landing situation. After all, you just took off from the same runway with sufficient performance to meet any obstacle clearence margins with a V1 cut, so you are not going to have any problems making the s/e climb gradient (I'm talking in general terms here, there will, of course, be exceptions.)
For the one and only s/e landing you are likely to make in you career, I for one would like the lowest Vref available. I'll risk the small chance that I'm going to have to go-around on this particular approach (if so, I'm having a REALLY bad day!!) and take the best landing performance I can get.
Hulabaloo,
Don't have the C/L in front of me, but I think you might be mis-interpreting. From memory the C/L gives the flap 30 option if you can make the approach climb gradient, which you can except in extreme cases.
I'll look it up and post a more definitive answer later.