Likewise, but I didn't spend too much time with 8100s at the time when they were current. My guess is that all of the 6100s and 7100s I encountered had a video card or Houdini in the PDS slot.
There were some Performa offerings (eg 6116CD) which never shipped with a PDS card. An original one of those would demonstrate whether Apple shipped the terminator in a 6100.
My recollection of the 8100's requirement for PDS termination comes from a tech note relating to PowerComputing and Cold Fusion.