[pr0xZen]

Is it possible to install OE on SSD using UEFI?
Any advantage in doing so?

I believe OpenELEC has supported UEFI booting since 3.1.3. So I see no reason why you shouldn't be able to install OE on an SSD. Might have to be internal though - some USB equipment can be a bit troublesome when it comes to booting, depending on its USB-SATA controller.

I myself is a Win8 user, so I'm not quite sure how audio handling works under OE. But under Win, UEFI handles does some of the HDCP instructions, thus HD audio won't work without an UEFI install. I've heard other stories regarding linux - but I have no idea if these were UEFI enabled distros. As you probably could deduct from my explanation of the differences - changing these settings (UEFEI/Legacy) from what they were set as during OS install - after the OS is already installed - will not ease any issues, but be likely to introduce new ones.

Beyond this - I suggest you have a read through the manual and other material on the NUC - these should give you a good idea about its capabilites, and if any of these are of use to you. You could also just go into "BIOS", browse through the various settings and look at the "Support text" when hovering over a setting (I believe F1 works in the more recent BIOS versions). Just a suspicion - but suspend/wake issues might be eased with an UEFI OS install. Again, I've had no issues here myself as I've only done Win8(.1) on SSD with UEFI enabled.

This is just a blind guess - but these boot issues with OE recently might be either a botched implementation of UEFI, or a conflict with previous install method (UEFI/BIOS) if this issue arrised after an upgrade.