I've got a manual mill with a 1hp motor on it. The problem is you have to start with like a 1/8" hole and work up from there. If you try to start with 3/4" it just wont do it.
With aluminum I can start with a 3/4" bit and be done in 10 minutes

hopefully the aluminum blocks should perform about the same as the copper and I wont have to worry about it...