It has been nearly 7 hours since iTunes Match started matching my library. Of more than 7,000 songs, around 1,700 have been marked for upload. Less than 10 were not eligible, this includes voice memos and music videos. Currently, more than 100 songs have been uploaded. Man! This could take ages.
I am also taking advantage of converting my existing mp3 collection ripped at 320kbps. The 256kbps AAC files from iTunes and 320kbps do not have any noticeable difference. This way, I can save on hard drive space.