I'm a huge fan of games that don't stick to the conventional 'level up, learn stuff' growth systems. Final Fantasy games in particular do this - the Sphere Grid from FFX and License Board from FFXII are amongst my favourites. However, I also like having a the normal experience and levels as well.
What I'm trying to do is look for a way to fuse elements I like from various RPGs into it's own system. At the moment, I'm using a Sphere Grid type system for increasing stats, and learning skills. I'm also implementing a method by which skills improve and level up, inspired by The Last Remnant. I'm also including levels, but I'm not sure to what extent. I'm thinking of having levels to limit progress throughout the Grid, or maybe as a prerequisite to learning certain skills. I've already removed stat increases from levelling up, as the Grid removes the need for that.
What are your opinions on combining these things together? Is it too much, too complicated? Are they great individually, but not so great together? I look forward to hearing people's views on this :)
Funny, I'm also considering soemthign like this I plan to have a skill grid system like you, have the player gain exp from fights and use the exp to purchase attribute upgrades, skills, skill upgrades etc. I had also planned to implement a counter that would let the player procede to the next level of upgrades only when they had unlocked a certain amount of upgrades in the previous level. I had also planned to include a quick levelup object that you could purchase with exp and advance yourself to the next level, it would be cheaper that the total number of upgrades youd have to buy, the only downside bieng it would cost alot of exp and not help besides fast forward you to the next level.