Rails migration syntax is intended to be database neutral. That is one of the main reasons to use it. The migration functionality also generates a database neutral 'schema.rb' file, which is intended to be the canonical representation of your application's current schema. This makes it possible for a new developer to simply run "rake db:create db:schema:load" and start working.

Since this particular plugin is aimed directly at postgres, I am not sure it really adds a great deal of value. It might be useful if it maintained the schema.rb file properly, but it does not.

So (at least IMO), I don't think this plugin is all that helpful. You can run straight SQL in rails migrations (and we do that whenever we need anything postgres specific).