Thanks, while we stabilise the save system it's probably going to be best to use new saves. I've put in a system this morning which will put up a warning about saves from old save versions to alert about them being likely to have issues. Hopefully with one or two more builds we'll be in reasonable shape with saves and then we'll try to be more careful in terms of backward compatibility. I would like to look into making them more compact as there is a fair bit of unnecessary data being stored in them too!