Yeah, metal cases tend to give a bit of a shallow sound, especially wedge style cases. Cases that are more simplistic with cone feet actually tend to be more resonant, possibly because much of the bottom is suspended from the desk, so the case is allowed to resonate more freely. Also, the layer of metal between the bottom of the PCB and the desk is a lot thinner than a wedge style custom.
My Monarch with SKCM Ambers is one of my nicest sounding and feeling keyboards, custom or not, and its case is quite simple.
Wedge cases give you a crisp but short typing sound.
