I am in a similar situation - I own multiple D300s and would like better low light coverage but with added twist. Better video capabilities in my dSLR. Therefore, I am leaning toward adding a D600 to my mix of cameras. I cover ~ 50 low light events per year including weddings and the build of the D300s is great for these types of events. I talked to many other pros and they like the D600 for weddings combined with either a D800 for the portrait work and/or a mirror less body such as a Panasonic or OMD for video and other 'stealth' coverage.