Glenn says at
http://glennchan.info/articles/vegas/v8color/v8color.htm
"The 1.000 mode will break many of the existing video FXs. Video FXs will deliver different and possibly undesirable or weird results. For example, the "Studio RGB to computer RGB" preset will no longer do what it says.
2.222 will give you the old school Vegas behaviour that you are used to. In most cases, I would stick with 2.222 so that nothing wacky will happen. "
So I ask that if to avoid nesting a 1.000 project in a 2.2222 one to get optically correct composting which Vegas8 FXs should be avoided?