Option 1) If mediocre is your worst experience, then that's not too bad. I agree with your assessment that teachers make all the difference. Another benefit: it cuts off at 5th grade, meaning he gets to go to middle school soon.
Option 2) Agree with a previous poster: find out what the difference is between this school, and option 1. Regardless of whether the kids are coached or not, this could still be a fantastic option for your child. My major beef with the kind of situation in option 1 is poor social studies and science... a gifted magnet can do better. It may not.
Option 3) I'm not a fan of asking 4th graders to design their own curriculum, because they generally don't know enough about the world to know what they need to know. So when you tell me their test scores are low, color me unsurprised.
In your shoes, I would eliminate option 3, and start vetting 1 and 2.
