A last thought on the Sony cameras. Most of them have two modes to reduce noise apart from NR settings. One is a multi-frame noise reduction mode that merges a number of images fired in under one second, without the need for tripod. Somehow it manages to stitch them perfectly even if the camera moves a little from shot to shot. The result is an image with less noise than if a single shot was used. There are two modes and I will post another thread showing 100% crops of a jpeg with no nr, one with nr low and then two images using each of the two multi image noise reduction modes.
It looks like the A99 can produce an image with more detail and less noise than the D600 if those multi-frame modes are used.