I got a discus dump from @snakeninny and start experimenting it.
If you are curious, you can find the commit here: GitHub - erickguan/discourse at discuz · GitHub
The progress may unfortunately be slow since Discuz got 297 database tables at this time and I can barely understand what is for what. The good news is the discuz has abundant data to get imported.
However I still need more samples here. If you want to import your large-scale Discuz forum into strikingly cool Discourse and are willing to provide the data, please contact me.