I will say one thing that bugs me is that at some point, you have to change classes if you want to continue advancing rather than change characters--you just kind of run out of improvements (in some cases, entirely, or in others you just run out of improvements that fit the character). And that has its own issues, as you may have a lot to give up (and that's wildly uneven: characters heavily focused on intrinsics, like the gunlugger or skinner, are going to lose a few toys at most; characters heavily focused on extrinsics lose a shitload) just to keep advancing.
What didn't occur to me, however, is automatically crossing off advancements you are unable to take due to already being "maxed" in some regard (well, it did, but the implications didn't). Can you really do that, and does it count towards getting to (or back to) the ungiven future advancements?