thx fr script, snarly.  I haven't yet applied SR4.

one can check if it reverts "on save" by examining pz3 file (pre-script) in text editor.  at bottom of node list it may say:

nodeInput "Filtering"
{
name "Filtering"
value 3 0 0
parmR NO_PARM
parmG NO_PARM
parmB NO_PARM
node NO_NODE
file NO_MAP
}
gamma 5.000000
}
}
}
locked 0
backfaceCull 0
visibleInReflections 1
visibleInRender 1
visibleInCamera 1

I'm guessing it will revert "on save" (without using snarly's script) or "on open" even if locked = 1.