This article does not cite any references (and is from 2010) so I can't tell if the author was aware that packrat parsing can support left recursion (PDF, 2008): http://web.cs.ucla.edu/~todd/research/pepm08.pdf
http://reports-archive.adm.cs.cmu.edu/anon/anon/usr/ftp/scan...
> It should be noted that while Packrat parsing obviously adds an extra layer of complexity over ‘pure’ PEGs, contrary to expectations it often slows parsing down when used blindly for every rule.
Especially these days, and really definitely in a lot of dynamic languages (cfe Ruby), the kind of allocation rate that packrat parsing produces has a significantly negative effect on performance. Applied blindly you're just trading n^2 performance for n^2 memory use, and that may not work out the way you think it should.