in January 2005
I was going to completely scrap over 100,000 lines of messy PHP code in my existing CD Baby (cdbaby.com) website, and rewrite the entire thing in Rails, from scratch.
I hired one of the best Rails programmers in the world
Jeremy Kemper (bitsweat)
Two years (!) later, after various setbacks, we were less than halfway done
in a mere TWO MONTHS
I rewrote CD Baby from scratch in PHP

It’s the most beautiful PHP I’ve ever written, all wonderfully MVC and DRY, and and I owe it all to Rails.

REASONS I SWITCHED BACK
#2 - OUR ENTIRE COMPANY’S STUFF WAS IN PHP: DON’T UNDERESTIMATE INTEGRATION
#3 - DON’T WANT WHAT I DON’T NEED
#6 - I LOVE SQL
Reading your reason #6, I see that you totally don't get what rails is.
I’m looking forward to using Rails some day

Useless post without a concrete illustration.

PHP handles integers wrong on 64-bit platforms
both
Unicode-handling sucks
Django/Python, they're at least getting there
Memcache? Fragment caching?
The Ruby interpreter is currently slow