Definitely aston. I love Rails and am using it for my personal project (http://www.babynamemap.com/). However, every time I've been given the opportunity to "rewrite" some big feature/app/module, the 2nd attempt is hugely improved. It's always tighter, even when rewriting in the same language.
Simply having a better understanding of the problem domain and total solution makes the 2nd pass a better implementation. I'd guess the bulk of the benefits Outside.in experienced are due that "rewrite effect". Rails no doubt contributed though since it is a nice framework.
Were the code savings due to the change of language or the rewrite itself? My experience with PHP and Ruby leads me to believe that basically anything Rails does can be done on the LAMP stack assuming you have the discipline.
This topic could be the basis of a great master thesis or paper. To what extent is a programming language and a framework useful for golf programming, ie as few lines of code as possible.
Simply having a better understanding of the problem domain and total solution makes the 2nd pass a better implementation. I'd guess the bulk of the benefits Outside.in experienced are due that "rewrite effect". Rails no doubt contributed though since it is a nice framework.