Did you know IntelliJ IDEA 10.5 supports XSLT 2.0? But it does!
Major new features are:
Support for XPath 2.0 syntax (e.g. if-then-else constructs, for-expressions and a lot more), completion for built-in XPath and XSLT functions
Complete support for XPath 2.0 built-in type system. Limited support for user-defined types
Complete support for XPath 2.0 and XSLT 2.0 built-in functions
Support for new XSLT 2.0 elements, such as custom extension functions (xsl:function)
New refactoring: Extract Function, turns an XPath expression into a call to a user-defined function
Some example screenshot