[Argorak]

Yes, but PyPy was not written in 6 months. For a rather comprehensive (but not so recent) benchmark, see:

http://etehtsea.me/the-great-ruby-shootout http://igor-alexandrov.github.io/blog/2012/11/05/yet-another...

MacRuby looses against MRI in many benchmarks and MRI doesn't fare as bad as many people say.

[kingkilr]

PyPy wasn't, but as a result of the groundwork we laid in building it, I (and several contributers) were able to build Topaz in under a year: http://topazruby.com/

[Argorak]

How much work do you expect it to be capable to replace MRI?