Hi,
yes, Fence 5 setting survive and going back to Fence 4 will work, including virtual directory.
Just make sure you don't check the box "Erase my settings" in the uninstall process.
However, and this, I didn't fully tested, "IT IS POSSIBLE" that if you go back later on to Fence 5 you'll have lost previous Fence 5 parameters.
Fence 5 "seem" to be completely compatible with Fence 4 settings (and that make sence in a developper point of view)
However, Fence 5 got new parameters and settings that Fence 4 is not aware of. Therefore, thoses Settings of Fence 5 will be ignored by Fence 4 and if you then later on go back again to Fence 5, it is possible that Fence 4 had deleted theses "unknown" settings.
again... not fully tested.
I did partial test though. I went from Fence 4 to Fence 5, then back to Fence 4 and now I'm back to Fence 5.
from my side, it doesn't appear I lost any settings.
Furthermore, it seem the last release of Fence 5 (5.04) have fixed completely the Multiscreen issue.
I must applaude StarDock here because only a week elapsed since I reported that huge bug on 5.01 and they already fixed it.
They reacted swiftly. I don't find back my post at that time so I cannot thanks them there.