Valor Breeches really isn't a replacement for RK Breeches - it's good for end game tanking when you're worried about damage, but it has less of a place as a DD piece.
So essentially you don't think the Valor's 3 extra STR (and I guess 3 enmity) makes up for the 2 DEX and 3 Attack on the RKBs? I ask this because honestly 3 attack doesn't seem like that much. Just curious.
Honestly, no I don't. 3 STR is 1.5 attack (depending on how it truncates). You're also giving up 1 ACC which may or may not be a deal breaker. If we had a YGK equivalent, I'd consider it as a WS piece, but with Vorpal or Atonement being the big WS's a PLD has, we need either Acc (for Vorpal) or Enmity (current, not +Enmity pieces) to see that max return for the WS's. STR has a place, but there's better options.
Dusk Trousers offers +14 attack. That's a significant chunk and would be a worthwhile replacement for the RK Breeches. It's also purchasable on the AH which makes it a great choice to have in place of Valor (as opposed to the obviously better choices of Homam/Aurum which are R/E and can't be picked up at the corner shop).
I wouldn't hold it against someone, but I definitely don't see it as a meaningful improvement.
Leviathan - PLD90, BLU90, MNK 90, DRG 78