I'll just chime in and say and say Prime Runners should be around 200+ karma. I know missions, which is probably where you saw the karma table you refer to, suggests 150+, but after having both run and played in 350+ karma campaigns, 20-100 just doesn't cut it. Just bear in mind that no matter what amount of karma your GM finally settles on, if there is no challenge, there is no fun. For us, even at 350 karma, there was still plenty of challenge and fun. At no point did it feel like we had broken the game and it really let us try many of the options available in the game that you will never get to at a lower karma level. By that, I mean you can do things in one character that you would have to split up over different characters at a lower karma level.
And before someone leaps up with "power gamer", we are not. Sure, our game finished with high dice pools but it didn't start there (I think 14 or so was the highest to start).