Yeah I think Carpe's system offers more flexibility and variety but I like the mechanics proposed by Kuro. Actually it could be a way to implement Carpe's system, i-e your have your job on top on your base class and you advance through this job via a talent tree or grid or whatever (or it could be like the merit system in XI, which was a kind of grid system but without the grid lol, I think the grid adds an interesting visual aspect and increases the sense of accomplishment)
For each job you could have several tiers of grids (tied to base class rank) and within each tier you could accumulate points to unlock say max 1/2 or 2/3 of the abilities/traits available (to maintain the customization aspect so a GLA/ Red mage is not exactly the same as another GLA/ Red Mage because they did not spend their points in the same slots).