I was wondering, are there actually any pros / cons to loading the game directly into the base game folder instead of the Documents folder?

How would you load the game from inside the Documents folder? I'm confused.

Windows NTFS file system uses the "master file table" [to store all the info/metadata] that means the directory and file hierarchy are just abstractions, so files inside the same directory or folder aren't necessarily [physically] stored nearby. (I am considering you are using Windows)

Documents > Electronic Arts > The Sims 3 > Mods > Packages

OR

[base game folder] > Mods > Packages

I've loaded mods from both and I can't tell the difference... I thought loading them from the game folder would be quicker but it doesn't seem like it. And yes I'm using Windows.

BaseGame/BinMod/Packages requires a special dll to work. Several years ago, EA eliminated that requirement and allowed mods, when placed in a folder in the Documents/Sims 3/mods/packages folder, to be natively supported (with a correct resource.cfg file present). Given the now accepted "official" method for mod use, folks no longer deal with the program files/game/bin routine anymore. In addition, you used to have to make sure it was in the correct game bin, as TS3 used to "boot" off of the latest .exe installed, that is, the latest EP/SP. That too was eliminated some years ago in favor of simply launching from the TS3W.exe, which does not alter location every time you install a new EP/SP.

As to telling the difference, as far as say load times, between the two method, it probably doesn't matter. However, as EA no longer requires one to "hack" the program files and insert a proprietary .dll to get the "old" system to work, it seems somewhat puzzling why you might want to keep going with a system rendered obsolete quite some time ago.

I don't know what you mean by that. I load them the same way, only from the base game folder instead of the one from Documents / My Documents.

Anyway, I take it there's no difference as far as loading times go. I'd keep them in the game folder since I tend to delete the one from Documents quite often.

The biggest con I've found is that mods don't load when you drop them in the basegame folder with the path you describe.

So I'm left wondering which meaning of 'con' should apply.

C:\Program Files (x86)\Electronic Arts\The Sims 3\The Sims 3 [resource.cfg is here]\Mods\Packages

Works fine for me.

Pros
- nothing that I can think of that the Docs method don't have

Cons
- when troubleshooting for incompatible or corrupt content using the "Clean user folder" suggestion, you'd have to remember to check both Docs and Programs paths. More things to check - more things you missed.
- uninstalling and forgetting to backup your Package folder, and then removing all files for the well-meaning step of "Removing all Sims-3-related folders", and all your CC is gone: POOF! Especially if you do it for ALL EPs + SPs, and the Recycle Bin cannot keep that many files of that big a size and thus would have deleted them permanently straight-away. So, no chance to even Restore. System Restore is unreliable when not dealing with the c:/Windows folder itself, if you're thinking of using that method.
- the biggest CON in my opinion after having to deal with users of all ages and all backgrounds for remote Technical Support is: allowing a user to touch the Programs path is a VERY BAD idea! You mess up the file structure in that programs path and you mess up your game so much that the only recourse is the Uninstall-Reinstall-Repatch tedious last resort. Compared to just renaming the user folder and letting Launcher create a clean one; in 2 easy-peasy steps.

But if you know what you're doing, no difference to the game, from its perspective. It would take the same amount of time, because the engine does not deal with files based on proximity, just by file location alone. The chunks can be all scattered and fragmented for all we know.