I've seen it for a while and I've come to rely on it; it is the single most significant feature that I miss after having moved from StylusStudio to Oxygen. XSL Debugging by stepping through the code is exceptionally helpful. Debugging XSL is a lot of work without an IDE to allow you to do things in a step wise fashion.
The other feature I miss is Stylus Studio's context awareness when creating XSL. If you associate an XML document with the stylesheet, then when you start a select attribute (for instance) it helps you along with everything that is directly in context. (children, attributes, variables/params), the axes (athough it doesn't go on to find all the elements along that axis from current), and functions. While it is occasionally less than helpful, for the most part its useful (especially since it adds parameter hinting for functions). I would also add mode and named template hinting when its appropriate.
Keep up the good work.
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