The two really big things I like about this system is that you can advance your character for a long time without running out of places to go, and that you can create a huge variety of characters and run mixed games. However, when you mix long term advancement and mixed systems you run into a problem: Force sensitive characters have practically no restrictions to how powerful they can become at any given thing, while non force sensitive characters have extreme restrictions.
You can throw force dice at a huge number of skills in the game. Social checks, athletics, coordination, brawl, piloting, gunnery, ranged, now mechanics... With the right combination of force powers and talents there are very few skills that you can't just roll force dice for.
So pretty much all of those skills are simply broken in a mixed game. A regular character can develop them to 5Y1G, which is a pretty major undertaking, and only affects one single skill. A force sensitive character on the other hand can add any number of force dice they unlock to the skill roll, which means there is essentially no limit to how many dice they can throw at a check. Not only that, but for a lot of checks unlocking the ability to roll force dice on them only takes 20, 30 XP in this or that force power, and after that your force rating simply takes over. You don't need to develop anything other than force rating to confidently attempt even formidable checks with skills you'd otherwise only roll 2G for.
It seems to become a problem when you let people develop their character for a long time. One of the main things I like about this game is that it doesn't have a level cap where you should really just stop playing and make a new character. On a non-force character you can always start developing sideways, and pick up new roles that fit how your character evolves. On a force sensitive character on the other hand there is always more force ratings, and all of them add into a huge number of skills. You inevitably break the game just because FFG didn't put a cap on force rating. Even if force rating was capped at 6 like other characteristics your character would easily exceed any non-force character at just about anything you can throw force dice at.
Ironically, the one thing where force users max out is actually using force powers. All aggressive powers are subject to an opposed check against powerful enemies, and your discipline caps out since you can't roll force dice on discipline. You don't need a dozen force dice to activate powers. That just leads to some seriously weird stuff though. For example, if you tried to use a mind trick on a Hutt you'd roll an opposed check against the Hutt's discipline, and then throw your giant force pool while only needing to generate two or three points to activate the power. The chance of failing this is pretty high. On the other hand, if you simply flat out lied to the Hutt and rolled your Deception+Force against his Discipline you'd easily beat him every time.
Likewise if you wanted to shoot people with lightning or throw things at them you'd end up making opposed discipline checks which can be very hard to do depending on the target. On the other hand if you just get yourself Intuitive Shot you can roll your entire force pool as part of a ranged attack, so you can generate ranged attack results that are beyond absurd, and still only roll easy checks at close range.
So, it isn't just the balance between force sensitive and non-force sensitive characters that completely breaks down, it's the force sensitive characters themselves that just fall apart because some of their aspects are subject to the skill and stat cap, and some of them aren't.
How do you get all that under control without just dropping a hard limit onto characters where you just say "Ok, this guy has too much XP, he breaks the game, make a new one"?