Making a backup of the mods folder is a good practice if you do not think something that you install will work, especially when you do not know where the files are or what files are being modified. Though I would check the comments of the mods you are trying to install and the description to see if there are any compatibility issues, or an installation path of the mod.
However sounds, atleast from experience and comments, don't typically have a reputation for messing up some ones game, except for the fact sometimes they just do not work because of the file size being too large, etc. According to the improvements in gore one, I do not see anything in particular flagging, assuming it is the right one you are talking about.
As far as ERO goes, I have no idea what mod that is unfortunately, so I have no idea what that modifies, so like I said, check the comments and description for compatibility and game corruption issues, and go from there with backing up your files and the such.