7 reasons I switched back to PHP after 2 years on Rails - O'Reilly Ruby
A lot of the points he makes I find familiar from Suneido. Most of the time you can reproduce the needed parts of some other whiz-bang system in less time than it takes to learn the other system. It won't do everything that other system does, but if it does what you need, who cares?
We've run into some of the same frustrations he mentions with our Rails project (eTrux). We didn't have the problem of trying to deal with an existing database (we were starting from scratch), but it always seems like there's something you want to do that isn't on the Rails easy path. But despite the frustrations, I think Rails was a good choice for this project.