So I managed to answer my own question about the kernel arg - it turned out to be necessary to get xfce to run stable. Next issue: no sound. The wiki says the analog audio out is not currently working, but audio over HDMI is, but I can't get either of them to work - I see an analog and a digital out in the pulseaudio mixer, but neither of them actually produces any sound. I've even tried plugging in a usb audio interface (which works seamlessly under Fedora on my x86 desktops), and it shows up in the pulseaudio mixer, but no sound. Any ideas?
Another issue: any media apps which use gstreamer throw errors about not having the right gstreamer plugin (for any/all plugins/formats), despite the fact that all the plugin packages are installed and gst-inspect shows all the codecs you would expect. Not sure if this is an arm/rpi specific issue or specific to this Xfce spin or what