Ok, I just tested on Inkscape 14574, which is a 7z, 64 bit version for Windows.
Results:
When snapping to smooth and cusp nodes are enabled, the center of groups won't snap to anything.
The smooth vs cusp node confusion still is happening. (Actually, since I've been functioning with that distinction for snapping, I'm starting to wonder if it matters which node type is snapped. When do we need to snap to one type and not another?)
I'm not sure about snapping the center of a group to a bounding box center. A snap does happen....yes, A snap happens. But the indicator says rotation center to rotation center, rather than rotation center to bounding box center.