ohh.. I've never looked with my left eye before. I actually used to use center dot focusing and backfocus button exclusively on the T1i. I actually just use half-shutter now. I don't use that button anymore, and only have it set to AE-Lock. I may change it, but we'll see. All the focus points are so good... with the T1i, I used to miss focus because I would focus with center point and then recompose. Apparently, that's how it is on the 5D mark 2 as well... only reliable focus point is center dot.
For my 2 lenses, 50mm 1.8G and 85mm 1.8 (AF...pre-D), the low low light autofocus seems slightly worse than the T1i, though.. A little annoying but fortunately there is the built-in AF assist light which I have turned off most of the time. Also I sometimes use my SB-900's AF infrared beam.
I love love the U1 and U2 memory banks
I have one set to capturing fast moving objects and another for portraits...I'll probably change the portraits bank to another setting for slower moving objects.. You can see the AF for fast moving objects thread for the settings.
I recommend changing the white balance, because you'll probably notice your pics are coming out a little green as is.
Ohh, and don't forget there is a feature to switch between DX and FX modes. I have this set to my Fn button. It's super for getting smaller file sizes, tighter crop (zoom), with full advantage of full frame sensor
I have the other button set to "My Menu" which I customized also for my most frequently used settings.
Ohh...and the built in intervalometer/time-lapse stills modes are awesome...one of them automatically makes it into a movie file for you
I'm guessing you WILL have dust issues, but it's not that bad and it's worth it. The problem has definitely gone away or way less frequent after a few thousand shots. Nikon cleaned my sensor when I sent it in for repair (dropped from tripod onto carpet and small mirror behind the large mirror got detached.) I have dropped my T1i a few times onto concrete and it kept on shooting just fine...so be careful not to drop your D600..! I'm planning on possibly getting the Crumpler wrist strap (Noose). I have a blackrapid strap on the bottom.