Personally I think you need to scrap any and all reasons for CHA. Make them a pure con caster.
In games that don't feature non-stop combat, HP isn't a huge concern for non-melee folks IME. Meanwhile, CHA is full of candy goodness. You don't need to be bribed into taking it. It is already bribing you. Meanwhile con has zero active uses, it isn't sexy.

And also, add me to those voting against Sorcs being the noob friendliest of casters. Metamagics are not intuitive or evocative. Picking invocations for a warlock is MUCH easier.