Mutt, I cannot speak for the 777, but when comparing the -400 and 340, to the 330, there is no difference.
Fire suppresion is a mute point. The fire either goes out or it doesn't.
If it goes out ....fine. You are now going to the closest bit of bitumen (and in a hurry) 280 min of bottle on an Airbus, or 195 on a -400. Irrelevant, you will be on the ground before it empties.
If it doesn't go out, the process is quite simple. You have 12-15 minutes to blow up your floaties, and ditch.
Weather. Hmmmm, I haven't done too many ETOPS flights, but I can assure you I have not seen too many people check the ERA WX after departure.
If the excrement hits the cooling apparatus, WX, RFF, ATC, all become somewhat irrelevant.
I have had an engine burp on a twin, 25 min away from a suitable strip, and I have had similar on a quad, 700 miles from Shemya in winter. I will take the latter every time.
Assuming the WX is reasonable, and you have the gas and terrain clearance, you can lose an eng 1 hour into a 15 hour flight, and still continue to dest (Legally. Though obviously not too desirable.)
Lose on on a twin, and you're making a distress call!