Dismemberment Plus is completely Plug and Play its addition or removal has no bearing on your save files whatsoever.
If you crash on load when DP is enabled it can be a few different things,
1. Wrong mod version to game version,
2. Out of Date Support mods = Harmony, ButterLib, UIExtender, Mod Configuration Menu (make sure they are updated to your current game version)
3. Make sure the DP dll file is unblocked on your machine. Just locate the file in your Module\DismembermentPlus folder, right-click, and if it shows you an option to click a button to UnBlock, click it.
If you have any issues with the mod hit me up on Nexus or my Discord which is linked from the mod page.