Just wanted to add our stats to the group data. DD9 is what I consider HG-HG+. She has lots of testing to back up the HG+ but doesn't have the drive that I associate with a PG kid. She's mostly happy fitting in with kids a few years older than her and not calling any attention to the fact that school work is much too easy for her. She's more the stealthy type who randomly suprises us with what she knows, what she notices, and the deep connections she's made.
DS7 has tested at more moderately gifted, but I'd actually put him closer to low-end HG based on what we see at school and on a day-to-day basis. He has the drive to learn and thinks learning is great fun and likes to talk about all the fun stuff he knows. He has always picked things up very easily and, because he's a 3rd child, has always been around higher-level learning opportunities and older kids, so he's had built-in enrichment at home.
Probably in part because we don't have the highest-level school district, both kids have benefitted from early admittance, subject accelerations, and grade accelerations. And both still need a bit more. The difference between my DD and my DS, though, is that my DD learns at such a pace and with such minimal repetition that we may need to continue to adjust her academic course every couple of years, whereas my DS would probably be good moving up another year in academics and staying there.