This looks incrediably, edibly, wonderfully so much better...
But there are still a few small issues...
The mechanic of Aim is a little awkward, at least in it's wording.
If I am understanding your intent correctly, this is how it works as it scales.
Full round action for one attack.
Standard action for one attack but full round action for full attack.
Move action for one attack but full round action for full attack.
It would be less awkward to simply make it take a full round action to take a full attack with X bonuses. This allows auto scaling of number of attacks as they gain them. Then simply make the speedier versions allow one attack with aim bonuses as a standard and then a move. I would also recommend adding in an immediate action step.
And 18th level just doesn't make sense. You're already allowing the class to mundanely hide in any situation (though it would be better to base it off of Shadowdancer's HiPS, the ranger version needs camouflage to work properly) but then suddenly converting it to being magic based instead??? Just make sure that the HiPS version you give this class works without cover or concealment and give them the Darkstalker feat at some point (allowing them to hide against scent and blindsight and such).
Also the 19th and 20th level abilities are ridiculously weak.
1/day death attack at level 19? Seriously? It's level 19. Just make ALL
Aim attacks be a save or die. This would make an immediate action Aim step very dangerous and tactically viable.
Whirlwind attack as a level 20 capstone? Seriously? Even with my suggested level 19 ability this is weak. Uncap it and swap it with my recommendation for level 19.