Urg, I'm sorry. We took our dd13 out of 1st grade for a similarly poor experience with an inflexible teacher who killed her love of learning. Dd still bears a grudge against the teacher.
Your ds sounds gifted from what you've listed but I imagine that the WISC will tell you more.
He all but told us our son wasn't that special and could benefit by staying just where he was.
That piece just gets my mommy hackles up. Possibly it is b/c my dd11's 3rd grade teacher said the same about her. She was "nothing special." Ouch!
Are you planning to homeschool long-term or just for now?