Dewey,
It's something I might consider after the Train Room Layouts are all completed, having the TIU on all my different track, I never even looked into the additional TVS at the head of each MTH terminal block. I do remember long ago Guns and I had a discussion about adding them to some of the real expensive engines. Having had absolutely no problems because the TVS was in both my DCS TIU's, I let the TIU be my major safe guard thru out the layout.
PCRR/Dave