well I know it's difficult but it's a multi million dollar game, the ability to have different stats between weapon classes is a must that will allow alot of different customization without completely getting rid of the armory system. and yes what you're thinking of with the grid system at tier leveling is exactly what I'm saying should be implemented (with of course, the option of "paying" for a grid reset).

I for example want to play a dark knight tank, something that might've been done in ff:xi but for stat differences couldn't, I would level the proper classesd to obtain the necessary spells/abilities to unlock dark knight, I do the title quest and unlock it. I equip dark knight as my title, and gladiator as my weapon specialization. Now lets say I'm a rank 20 gladiator, if the stats were static I can assume (just for examples sake) my STR to be 30, VIT be 40, DEX be 30, MND 20, INT 20 or what have you. Now I equip my dark knight title, it grants a +1 STR/VIT and lets say for every level of gladiator I have equipped so now I have STR 50 VIT 60 DEX 30 MND 20 INT 20. as I progress my dark knight title the +1 str/vit becomes +5str/vit +3 dex for every level of gladiator I have, so as a rank20 gladiator I now have 130 STR VIT 140 DEX 90. now that is VERY VERY rough example of how the system could work, please don't take it at face value. you could see the clear benefits of getting an advanced job and how it might be used to augment any base weapon class. (marauder being very heavy on str, pugulist being a balance of str/dex etc etc)

Then again I might not choose to take those stat bonuses as my title bonus and instead opt for something along the lines of a passive ability that makes my atk buffs last longer, or my absorbs drain massive amounts of stat you see? it's pick and choose and definitely allows for greater customization of the job you want to play.

And really balancing the different titles and tiers it's all done with percentages, it would be difficult I'm sure but not impossible, it only took a day for the community to come up with that leveling scheme. the best way to possibly do it is to give a percentage type bonus, tier 1 giving you 1% (for dark knight lol, I use it for all my examples because thats the class I love to play) for str/vit with a gladiator spec, but giving you a 2% str bonus with marauder spec. Percentages are easiest to implement and the easiest to balance out after releasing. nerf's or boosts would happen after implementation I'm sure, but that just goes with the territory of making an MMO.