Enlarge Weight Limit 10 will allow a Gunslinger to carry 130 additional seeds. (EWL10 gives +2000 weight)
Since they don't get the same Tao Gunka bonus like other classes, they're still just as vulnerable to burst damage as they would normally be.
I think this change isn't asking for a lot. If implemented, it would only serve to give GS a slightly better chance in events that aren't just WoE (ie PvP, GvG, BR, LMS, LTS). ~200 seeds and low HP essentially relegates the gunslinger to a tool instead of a competitive class to main. Even with the additional seeds, I don't think gunslingers are going to be able to suddenly dominate, only be a little more useful.