I was a product of the GATE system in the PUSD and I don’t think I really got anything extra out of it. I remember being pulled out of my normal class a couple of times a week to meet with a teacher and a group of 4 or 5 other GATE kids. Like CBad said, I didn’t like being singled out and having to leave while all my friends were doing something else.
The real benefit of the advanced programs in PUSD were when I went to middle school. In 6th grade, they enrolled me into the pre-algebra math class. This set me on my way to finish two years of AP calculus by the time I graduated high school.