There are very few Race/Class combinations that outshine other race/class combos on the same faction.
As far as gnome 'locks in particular, there doesn't seem to be any reason why they'd be any worse off than their human counterparts. (In fact, the gnome racials seem to be a bit superior to the human ones at first glance).
The added bonus of this, is you and your girl will start in the same spot. (Dwarves start there too, but I don't think you can be a dwarf warlock).