Even if it would be the same in theory (which makes sense to me), there’s the matter of not needing so much fuel on board.

Even if we assume the cost of the fuel is equal to the electricity cost (though I imagine rocket fuel is pretty pricey), you’re also saving on the cost of the larger fuel tank, and the cost of propelling the full fuel tank.

That’s my entirely amateur opinion, anyway. Plus, it’s cool as hell, which has got to count for something.