Well, very high/low stats is why I switched to point-buy.
However it shouldn't be a problem if everyone is in the same league. Suggestion: figure out how many points the characters would be as if they had used point buy. If Mr. High is 20 points higher than Mr. Low then you're going to have a problem if Mr. Low doesn't have a very good sense of humor or is at all competitive when he games. In such a case, my advice would be to approach Mr. Low and say "Look, Mr. High is going to be kicking butt and taking names compared to you. So I'm going to give you a minor magic item at the start of the game that ties into your character's background. As you roleplay and advance, I'll be adding to the item's power."
So, the guy will start out with, for example, a masterwork sword that was given to him by his father. IF the character, say, defeats the [insert level 2 challenge here that ties in with his background] he becomes more attuned to the family sword and the sword becomes +1 for the character only (to prevent him flogging the thing).
So, in exchange for relatively feeble ability scores, he gets a magic item he doesn't have to find or pay money to get. He also gets several tie-ins with his character so he gets to become the "star" of the game now and then, even though the other guy is getting all the combat/skill successes.