I am starting to experiment with ZClasses, and hopefully eventually Products in Python. I am wondering how easy it is to migrate at a later date. If I were to create a ZClass based Product and start using it extensively, how easy would it be to migrate to a full Python Product at a later date? If the two have identical or similar methods, is there a way to change the instances over to the new product.? Similarly, if I subclass standard Zope objects like folders and documents, am I likely to have problems in the future with new versions of Zope? In any case I am expecting that the Product will be continually evolving. How are instances affected when new versions of products are installed? I am not too familiar with this stuff and dont want to work my way down the wrong path. Tom