The only diffence I know of, aside from the X5 being a 2005 model and the SS a 2006, is the SS model has the Summit Skin. I have not seen any of these stands yet except for on the internet and in catalogs. I don't think you will find aroomier stand, that is safe, made in the USA,that comes with a decent full body safety harness for less than the Goliath. Summit also has excellent customer service.