I take it that no one has hit the bug that stop uploads at around 18,700+ tracks, just shy of the posted 20,000 limit. From my experience with the upload program, it scans and upload the first item of every folder, then the second items, then the third, and so forth. And it sees to also upload the most recently accessed items as well, so if you tend to play certain tracks often, those will be uploaded first.
I would love it if Google will double the storage too? Then I can get most of me library available vi the cloud.