Makki, yes, there are people who try to game the system. This is why you make them come up with a DAMN good reason why they're character is like that, or you kick the player down the stairs and make them redo their sheet. That problem becomes a non-issue with the most basic DM oversight. This is the kind of things DMs are supposed to be doing anyways, regardless of setup. If something feels hinky, tell them no, and if they can't deal with that, do you really want them in your game? Hell, even with a regular build you have people who try to minmax their way to uberness. I had to explain to someone why a troll drake warrior's way adept wasn't going to fly, since in his dracoform he could one shot anything short of a battleship, but he could do absolutely nothing else besides combat. It was, in a word, obscene. So yes, DM oversight is key. It always has been.
JustADude, not really, since I know the BP rules, and I know the karma advancement rules, and I don't know karmagen, and I certainly don't know German, nor do I particularly trust an errata of a German product translated into English. And I think anyone who's ever read a manual for something built in another country can agree with me on that point. Again, there's a mechanic already there, that works. Why go through a whole bunch of trouble, involving foreign errata, when you can take the system already in place, relax availability a bit, and then give people X Karma and Y nuyen? And, of course, administer headslaps to people who try to game the system. But hell, that's half the fun of DMing! I use my hardcover books for headslapping. Makes more of an impact when that DMG whacks a player wanting to be a half-troll pixie sorcerer doesn't get the hint.