It's an honorable thing to mention alternative and/or competing technologies on a project website. It's even more interesting when this is done on a promiment page. Here's a few of those who do it:
- Linux Target Image Builder (LTIB)
- Liferea
- vnStat
- LinkChecker (linked from main page)
- Gittip (project README file)
- vcs (a top-level section in the official documentation)