No. There is no way to gear Quick Shot to do more damage than the DA from /WAR, the haste from /DRG, or the utility from /RDM.
Speaking as a 76COR, the main issue here is the garbage bullets NIN has access to. QD is based in very large part on the total DMG from Gun+Bullets. Although NIN can use some respectable guns like an unlocked Coffinmaker (DMG:40) or a Shark Gun (DMG:39), you lose a VERY significant 15DMG by only being able to use Iron Bullets as opposed to COR's standard Steel. You're also lacking COF AF hat, which is a sizable boost to QD.
I do kinda want to fool around on NIN/COR, but it's really a novelty and not much more. /DNC, /WAR, /RDM - they just offer more.
/COR can get access to Slug Shot, and NIN has access to enough good ranged gear through AF/AF+1 and random pieces that you can make a solid Slug set other than the lackluster ammo, even considering the mediocre C rank Marksmanship skill. Again though, more of a novelty than anything. Even if you can outdamage Jin (wouldn't be that surprising, especially on piercing weak mobs) you'll be less consistent thanks to Slug's Accuracy penalty (exacerbated by C skill) and you'll have to spend money on ammo to do it.
One thing that doesn't tell the whole story though is "/WAR gives more DD". Don't forget it's not all about the damage you contribute, when you also have subjob strength buffs to help a party. Some refresh on the mages with Evoker's and a DD roll up front (even a subjob strength Chaos, Hunter's, or Samurai roll can be quite helpful) aren't something to ignore. You can only have one roll on each party member at a time, but you can cycle multiple rolls to target different members (e.g. one on healers, one on melees). Perhaps there's some situational use there for a non-tanking NIN to help the party with /COR buffs, Innin DD, enfeebling and elemental ninjutsu. Edited, Jul 2nd 2010 12:52am by Anza