I'm using it for my panel editor at the moment but I can extend it for my other editors. It allows me to create an exact memory clone of a current engine object, without having to manually copy over properties.

As for your same session argument, yes this is true that the object will only remain while the current instance of the engine is 'alive'.

As my editor is just the visual part, it retrives the data from an external source, where the data is also cloned.

You don't have to mark them if you don't want to, lol.

Btw, I know that it's off-topic, but have you experience with the 'var' keyword in VS 2008?