I have LR 4.3 on one computer and LR 4.4 RC on another and there is no binary difference in the contents of the files between the D600 camera profile files from LR 4.3 in December and the D600 camera profile files from LR 4.4 RC in Feb 2013, so the difference must be elsewhere, outside the profile files, and could be imagined or a bug or change in some other aspect of LR or video drivers or monitor profile or the lighting of the pictures, themselves.
Presumably you’re comparing camera rendering with LR rendering with all the in-camera-toning settings at their defaults or zeroed and you aren’t using ADL nor noise-reduction, either, right?