Autocompletion in the Xtend editor is quite excellent, you might want to try a recent version. The last time I tried the Scala IDE (during the first Coursera lecture), Scala's autocompletion suggested may invalid proposals. It felt more like the editor was guessing about types than actually doing proper type analysis. If you happen to have a Java stack trace from Xtend code and click on a stack frame, Eclipse will open the Xtend file and highlight the proper line in your Xtend code.