> Rails 1.x to 2.x or 2.x to 3.x Yep. I stopped choosing Rails for new projects after 2.0 but inherited a few codebases with newer Rails subsequently. The pro

> Rails 1.x to 2.x or 2.x to 3.x Yep. I stopped choosing Rails for new projects after 2.0 but inherited a few codebases with newer Rails subsequently. The problem is not necessarily just with Rails, it's that gem authors don't necessarily have the bandwidth to support high quality versions of a gem for both versions. So if a gem is coupled to Rails' inner workings (as many are -- some unnecessarily) there is added downside to not upgrading even if the older version is working fine. It does look like the APIs are finally stabilizing. I'd like to see Rails gravitate more toward a series of conventions defined by contracts, not abstracted away into implicit behaviors.