Neither would Defoe. He doesn't play wide, so he'd be looking to play down the middle and to stay there, when our best success has been with three players who interchange and work their bollocks off. For the right price he'd be a good "option" but not the solution. At least Vardy presses all game and will pull wide if he needs to, but his age is well against him.
You're saying Vardy thrives on space, so does Defoe. He's maybe got a bit more of the "fox in the box" about him, but his game over the years has been heavily reliant on his pace too.
We should be spending big on a younger player who fits the system AND is a regular goalscorer, but we've said this all season to much derision for some stupid fucking reason.