I've been using Windows 8.1 on my Dell XPS 12 for several weeks and the only issue I've had was I lost the ability to use an extended display with DisplayLink. I heard about the new DisplayLink v7.4 software and decided to try that. Installed it and it didn't work, so I followed links to this article:
http://www.displaylink.com/support/ticket.php?id=297, which recommended the DisplayLink Install Cleaner tool which seems to have "cleaned" Wi-Fi capability off my machine. I've tried restoring to a previous restore point in Windows from a few days before I installed the new DisplayLink software and nothing's working. At this point, I don't even care about the extended display anymore I just want my Wi-Fi connectivity back!!!