Matt Mahoney has a neat page compiling text-compression benchmarks:

http://mattmahoney.net/dc/text.html

https://news.ycombinator.com/item?id=6001489

It's linked in the OP but easy to overlook.

Here's how the prize winner compares with generic tools on en-wiki text (from Mahoney's page):

              Compression
    	      Ratio (in/out)  Time (ns/byte)
    decomp8   6.27            324,000
    xz -9 -e  4.72            2,482
    bzip2 -9  3.94            379
    gzip -9   3.10            101