I'm very glad that people in the linux community are working to support HiDPI displays. I recently tried to use a new MacBook Pro Retina with linux, and my outcome was that it was marginally usable with a HiDPI display.
Kinda shameful that DPI scaling has never been a thing in Linux. I'm glad it's being worked on. I'll keep a Linux install kicking around once Wayland and/or Mir land with this stuff.
It's not a hard problem at high pixel densities. We should be able to just specify the display density in DPI and sizes with device independent units. We've been doing this with print for ages.
Glad to see someone's working on it, though as an end user, I won't care all that much until it lands.
For what it's worth, I've been using the `-dpi 239` flag in xserverrc and openbox scales just fine for my Chromebook Pixel. Some apps don't, but for the most part, it works for me: