You say that Link2SD moves one's apps and widgets to the SDcard. Which is exactly what App Manager does. So I don't really understand how these two things are different.
I know this is a little old, but I was just reading through this thread and would like to add a little more clarification to this.
Link2SD helps with space so much more than App Manager because it has the ability to move all data, including the application file, the dalvik-cache file, and the library files for the app to the sd-ext section (a sd partition). (BTW, Partitioning is dividing a physical storage space in to different logical storage spaces) It moves all of the app data from it's original location to the sd-ext and then creates links in place of the original location to that data so that it is all connected back to the internal location and continues to function. Link2SD also has the ability to move apps that can't normally be moved and automatically move apps to the SD as they are downloaded and installed, saving you time and space so you can keep spending hours in the Play Store clicking install app after app
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Ooo I want that one, oh and that, and yeah this one here, ect...)
App Manager on the other hand leaves data behind. Depending on the application, that can leave a bit behind and still take up a bit of your internal storage memory after quiet a few apps. Also it can't move certain apps. Another thing, apps are moved to the User's Fat32 section, which when turning on Mass Storage on your device, unmounts that logical section of space (the space other than sd-ext unless your card isn't partitioned then it's all the space) and mounts it on the computer, making that space and content unavailable to the device
Take the app Netflix for example. With all of it on my internal memory the total storage is 26.96MB. Now if use App Manager and click Move to SD I get 1.21 MB left behind. Another example is Google Maps, 19.82 MB. App Manager won't let you move it to the SD card but Link2SD will let you move any app. Saving you room for apps that you do want on internal memory.
I hope that this helps explain so differences and helps new comers to the scene
This is my knowledge and understanding of this, If I am incorrect in any way please feel free to correct me, as knowledge is useless if it is incorrect.