These are only my opinions, and are in no way final:
I'm not so keen on making the TNGs wear 3rd job equips because they are, technically, 3rd job equips. It's the reward the 3rd/Trans classes get for going through all the trouble of leveling to 99, twice, then to 150.
Before I go further, I only think its fair to mention that these classes have been the way they are because despite being a first-job, they possess skills that can compete with those of trans and 3rd jobs already (i.e. Ninja's CCS, Gunslinger's Desperado, Taek SLS). It's only a matter of boosting their effect to catch up to the different rates and demands of a server like ours--which we are already in the process of doing.
I'm going to have to disagree with the suggestion to include bullets and grenades in the mall. I'm currently compiling a list of revisions for all the TNGs (some, in preparation for their possible "next jobs", including aspd) and if the revisions prove to be sufficiently strong, it might be better if ammunition wasn't so easily available. I'm thinking of keeping the old bullet/grenade NPCs in Einbroch since there has been talk of making the 3rd class skill-requirements monster-droppable instead of being sold via NPC.
As for the card slot, I've mentioned it to Njord sometime ago. I noticed it was severely lacking too since, you're right, cards do play a big factor. However, I was thinking maybe we can leave that feature for the next job as a sort of "thanks for getting this far" present. :p
Elemental bullets sound like a great idea but, for fairness' sake, we might have to limit it to a couple of elements only. If the player is after elemental long-range fighting, there's always the Archer class. We don't want a job that's basically a clone of another, just with different skills. So... What do you think about status-bullets?
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Note: This thread can be even more useful: All you players can help us out by listing down what you think currently needs work with the TNG's. Help us help you by telling us what else you think needs boosting or nerfing in this thread!