The reason the offhands are so much better is because they are i70 and the gear is only i60. You absolutely do not want an NQ offhand though, since no amount of extra melding is going to come close to making up the difference in stats lost by using NQ (you already need to nearly fully meld the HQ offhand to hit 4-star caps), and you won't be doing 4-star with an NQ offhand without some serious buffing. NQ'ing the i60 gear isn't that big of deal since they have 3 free slots and it's not much harder to make up the stat loss on NQ with extra/higher materia.