Commercial customers of XMF-Mosaic (from which the XMF engine is taken) include (in no particular order) BAE Systems, Artisan Software Tools, BSkyB, BT, Citigroup, Lockheed Martin, SELEX Avionics Systems, Ultra Datel, MCM S.P.A. I am not sure why you view XMF as esoteric - it contains standard OO features found in languages such as Java, metaclass facilities found in languages such as smalltalk (al