Due to the speed of the game 6 man parties will never be good again. Its as simple as that. If you do not increase the speed of XP then people will go to other places that are faster, we have seen that from experience. If you make XP higher, you level to fast, in the Double XP campaigns for instance there were parties in Qufim killing Worms & such for 1k XP a kill before you even think of counting in the XP from chains, having to change camps every 5 kills. This does not make it fun or enjoyable, and the game itself simply does not have enough mobs nearby that do not aggro or link but also scale in level enough to support not having to move every 5 kills with an accelerated XP rate. So in the end you come to the fatal flaw that is FFXI's leveling today. Its impossible to truly fix in my opinion.