The high mass has a base plate that is twice as thick as the standard base plate (3mm vs 1.5mm)
IMO it does a change the tone a lot and i to am not a fan of it.
Pretty much all my basses have a bent plate bridge now!
Are you sure about that? I was comparing the high weight bridge to the older American series bridge, not a true vintage replica like that found on the reissue basses.