I never used Folder Portals prior to this, but testing right now, touchpad scrolling (I also use Precision drivers) on them seems to work flawlessly.
Folder portals have quite a few advantages, not the least of which is more view options:
They also do better with temp files created for applications while the original is open for edit (all MS Office apps do this for example). Temp files can mess with how Fences deals with the original icons in a Fence - often bumping them out as Fences sees them as new\ different once saved.
One of the main advantages, and pictured above, is you can open a folder portal to any mapped network location - a centralized one for example. In the image above, anyone here can get to that folder and add \ remove \ edit files there.
So, as a workaround, what you could do is create folders that match your Fence names - say in your Documents folder - and drop your icons in them, then create folder portals to them. Any new icons you place on your desktop can be dragged \ dropped there henceforth.
Stardock Support Manager