As games get higher quality and resoluton gets bigger (4K) more memory will eventually also be used. I'm planning on having upto 4 Monitors 3+1 TV at the best point, so the fact that the 6GB model costed me around $100 more than te 3GB isn't really too much to hassle about. Eventually at some point I will most likely grand benefit from it. And in future I will get another GPU to run with SLI.
I chose the i7, because of the more threads which will come handy, since I tend to do a bit of editing work. I've had an i5 for 2 years now and think it's great, but I wanted to have the top of the list this time, without going insane extreme.
I have the H105, I'm going to put some of the best noctua fans on it so increase preasure and recude noice, so I'm not too worried about it being loud. Theese are the best fans avaible honestly :p