No save option during stealth sequences or generally in stealth-heavy games. Allow me the option to either improvise and enjoy messing up or plan and execute and test every section of a stealth route carefully without having to replay the mission a thousand times, especially when the slightest hiccup will have the whole mission going awry. If that leads to some people save-scumming their way through the entire mission, so be it. Let them play their way.