As it happens, I agree that trading off GPA for appropriate instructional challenge is quite reasonable and even preferable. Learning that natural giftings plus effort equals growth is a pretty critical lesson that many GT learners do not experience until much later in life, if at all.
And my point regarding child responsibility is simply that one need not take ownership of decisions that were taken out of one's hands. In my opinion, decisions that involve minors are ultimately the responsibility of the adults, both by statute and morally.
My own experience with acceleration was much as you propose, although not so much for the purpose of getting out earlier, but simply to be in the zone of proximal development with regard to academic placement and rate of learning. I did not actually reach the point where instructional challenge required learning EF skills until graduate school, and did not actually learn to exercise those EF skills until my third round of graduate studies, with assistance from motivation and frontal lobe development (which continues well into one's 20s).
