fns720 -- looks lovely!
I've been lurking in this thread for a while because I've been hideously busy with a KickStarter project but it is of great interest to me. I'm glad to see this topic is heating up again :cool:
Perhaps the solution to the issue of uneven cooling in the "lee" of the printhead where it blocks the airflow is a small fan on the printhead that blows directly downwards.
So the setup would be that the fan is on the left side (the reverse of fns720's setup) and the fan is mounted to the printhead on the right side, blowing directly down, perhaps with a duct.
My current setup has two fans on the printhead, one in the standard position and one blowing down vertically as described above, and seems to work well. You can see it here: http://www.thingiverse.com/thing:164499
It is an accessory mount ring for the hot-end that makes it much easier to mount things to it, and it was designed with fans in mind.