I tried Endless 3.4 on my X2. There does not seem to be much difference from earlier releases. I have not installed it, but ran it live from the USB installer.
Internal sound still does not work. Sound via Bluetooth works as does sound through HDMI. It appears to me that memory usage still rises very quickly and Endless seems to just overwhelm the limited resources of the X2. My trial ended after about 10 minutes when the system either froze, or simply became unresponsive.
I will probably go ahead and install Endless 3.4 on my X2 to see if it runs better installed than it does in live mode.
bill