Will there be an option for a handicap? I think for some of us, it will be an absolute necessity to impose either a handicap, or an optional penalty to balance skill levels.

Ya, that can definitely be added. Any suggestions for the handicap? Less lives? Harder creeps? Less gold per creep?

What about the skills you have here, but turned to negativ. So instead of extra damage you will do less damage. Extra starting gold turned to less gold, Harder creeps, well, should be the same. All these handcaps will give some extra points. Perhaps a flat of 300 points per skill, or a few percent.
You could also use the battle settings from GemCraft Labyrith, so people can choose their handycap before the map starts.