For large scale I think I'll choose Oil washes every time, the citadel washes seem to mottle horribly on big flat areas and of course the 'coffee ring' staining etc. with over lapping coats and the like.
I still like the citadel ones a lot, but the oil wash is very very useful. Just make sure you're well ventilated and wear something over your face. I got dizzy and a little queasy last time I used them, white spirit is strong.
Edit: Deadlift, yeah I was totally going for a colour modulation style when I sprayed up this one. It's about 6 layers of Minitaire mixes. Starting with red-brown/dark aqua blue for the base/shading, then mid tone reds, then fluro yellow/bright red on the focal points (but those coats seemed to barely show up, I assumed this was the black primer and previous red coats absorbing them).
Here's a shot of some of the masking I did
[URL=http://s235.photobucket.com/user/Usiel-40K/media/Angels%20of%20Baal/BaalTankMasking1.jpg.html][/URL]
[URL=http://s235.photobucket.com/user/Usiel-40K/media/Angels%20of%20Baal/BaalTankMasking3.jpg.html][/URL]