Well, good or rather EXCELLENT discussion. I am going ahead with the PSX-1AC on my 8 block railroad. I'll put them ahead of the TIU, between transformer and TIU. Until some brave soul does thorough testing to see if these degrade the DCS signal (and for that matter TMCC and legacy), I think the protection will have to be on "the wrong side of the tracks".
What a friggin hobby! My trains drag me into every corner of the known hobbyverse!
Don