I actually think Dagger is MORE useful than Marksmanship these days. Especially for someone who already has capped dagger on DNC (and likely has merits too). With good options like augmented Yataghans (my best has DMG+8/Crit+3% augments) and Twilight Knife and solid melee gear, COR isn't bad with a dagger. I find it better than the subpar damage and extreme cost of shooting for TP. As for WS, Leaden Salute and Wildfire are magical WS which are not affected by Marksmanship skill. And Evisceration is arguably better damage than Slug/Det both inside AND outside of Abyssea (not to mention cheaper since you're not using ammo).
So yeah, I personally either melee with dagger for TP, or simply get my TP from QD and regain from rolls/gear/atma if I'm focusing more on buffs (especially viable on Abyssea NMs, or if really focusing on hitting strong buffs thanks to the new XI roll changes).
As for AF pieces, head (and +1 head) is still the number one Quick Draw piece, so that's still a must. Body and Feet used to be must have at 75, but are now outclassed. Since the head is from the third AF quest, you'll need to quest the weapon (AF1) and legs (AF2) as well in order to get it. Can safely skip the other 3 pieces though.