LA Lex

I have a 4th generation navigation, and enjoy the ability to do the manual override. I currently have the 5.1 map DVD. I understand that the new map upgrade to 7.1 disables the ability to override the system so that you can enter information while moving. My question is if anyone went forward with the upgrade to 7.1 and do they think the map update is worth losing the override ability.

Does anyone know if the 5.1/7.1 disk works on the Generation 4's