Interesting. As another data point, my DS6 (untested, crazily mathematically precocious, but I would guess much more audio-sequential than visio-spatial) has been learning piano since September. He's doing well, but not, I think, exceptionally well. (That is, he seems to be further on than other children I know who started at the same time, but he still sounds like someone who started less than a year ago!)
I had a son start piano at 5, and it took a while for those motor skills to develop. Once they did, he took off. For him, he enjoys piano but does not choose to practice on his own even at 9. He does play on his own - he composes, improvises, pieces together music from video games. But he wouldn't necessarily pick up his Clementi Sonatina books and start cranking them out. He did eat up a book of Harry Potter movie music about a year ago though!
He does have certain songs that he eats up, and we do go in phases in terms of highs and lows (he just hit the 4 year mark).
I also consider him highly VS (although, he does seem pretty balanced in his GT-ness. I'm too cheap to have full testing done but suspect he could be a DYS candidate on a good day.) Anyway, he is precocious as a piano player. A lot of his work in piano has to do with hand size and technique.
All that being said, we go to a large, somewhat intense and competitive music school. There are a few kids DS's age where he is at. Some are clearly very gifted across the board as well. But some of them are just very intense and are working twice as hard. We practice a low to average amount for our demanding instructor for DS's level. But the teacher has pulled me aside and assumed we were practicing a lot more than we are. Anyway - it's interesting to think about. And clearly the GTness has given my kid an edge in learning piano. But he doesn't have the passion for it some other kids have.
