Re the clean vocals..
This is a tough one because altho they do still sound a bit flat ( which maybe down to being over processed or not processed enough ) they arnt really being sung, its closer to a spoken part. but I do fully agree with the need for conviction and aggression generally in that department..
Re the mix in general
I does sound cluttered in parts, but there is very little to lose, other than when the 2 guitars are playing the same part. I'll try to re-eq the guitars so they're not fighting for space so much. I kinda thought the bottom and of the mix was about right ( kick and bass guitar ) after listening on my hifi, but i'll be happy to be advised otherwise.
as far as mixing on headphoes goes. I've being doing it for a while now, but never with this much going on. ( i've been doing mostly folk acoustic / female vox etc etc ). And i've just got some new cans ( beyerdynamic dt880pro )which im getting used to. I have no option regarding this, but I'm happy to continue because its worked for me in the past, and I know many people do it very succesfully.
thanks again, i'll update if I get another mix done in the next fewdays