^^Congrats man! It's amazing how good this sensor is at those ISOs.
I'd say roughly ISO 800 on my mkii was not as good as ISO 1,600 on the D800, maybe around ISO 2,200'ish. That's staggering and that's at 100%, so scaled down it is easily ISO 2,200 or there abouts. Noise cleans up very easily in LR and the noise pattern at sane ISO's seems 'smaller' in size than on my mkii so even with NR applied it resolves more detail.
One niggle so far. Low light focus isn't as good as I had expected and isn't as good as my old mkii centre focus point in some situations. To be fair, this was with large light source behind the subject. I've set mine up for mostly 11 point AF (all cross type I think) and get perfect AF when it hits. I have had to increase my minimum shutter speed when hand help for sure.
Canon colours still rule as far as I'm concerned, I'm gradually cooking up LR recipes to get me close but on the flip side I am liking the tones, it's just a different look. I still think that the 5Dmkii and iii are great cameras but this is super great.