Personaly I wouldn't balance a Cha boose with anything but a Con, Dex or Int penelity. Str & Wis are of little importance to sorcerers.
D&D ability scores tend to be a bit lop-sided this way, a -2 Str, +2 Int race is GREAT for wizards, while a +2 Str, -2 Int race is GREAT for fighters. According to the DMG the +Str guy is getting the better deal, but he'll loose skill points. The wizard will almost never need Str, since his spells can acomplish everything he could with a higher score easily (tenser's floating disc, Spider Climb), so really he's getting the better deal in this case.
I'd give 'em -2 Str, -2 Con, +2 Dex, +1 Armor, +2 Cha, 30' speed, Darkvision. Should work out fairly well. This is still very good. +3 AC (Small, +2 dex, +1 armor) and +2 to Cha, and darkvision and no speed reduction.