So my new DX80 arrived yesterday and I've been having a play. Unfortunately an Xmas/NY bug has caused an ear infection leaving me temporarily deaf in one ear, so SQ comments will have to wait - for now this is just my experiences regarding GUI and usability in light of previous posts regarding fw issues.
My unit came preloaded with fw 1.1.4. so have left as-is based on comments re fw version 1.2.
I am using x2 ByteStor Pro 128 GB Class 10 cards which were just £29 from Amazon UK. Not the fastest to write to based on transfer rates via a USB 3.0 reader but perfectly usable for audio purposes.
I do all my file transfers directly via my Synology DS412+ NAS because it has all my music on it and has an inbuilt USB 3.0 port which my slightly ageing iMac and MacMini do not.
Because (for reasons I cannot explain) Synology only support FAT32 and not exFAT formatting for external drives, I was forced to used FAT32, however this seems to be the better option. As I don't have any DSD files and am not a Classical fan, the 4GB file size limit poses no practical limitation and I was able to partition the cards as single volumes of 117GB usable capacity.
Scanning both cards, one full, one half full, took a few minutes on first insertion, but once the file log was written to each card, the both work instantly if removed and reinserted.
Having played around and flicked through as many menu options as I can think of, I found the GUI to be perfectly responsive, with no noticeable lag.
As my two cards have hi-res and compilations on one, with single artist lossless albums on the other, putting the DX80 into 'all music shuffle' mode inevitably requires jumps between different folders, cards and separate log files when skipping forward or back between tracks - again this is performed instantly with no detectable delay.
I can also report that gapless playback of 'mixed' electronic dance albums works flawlessly. I had not expected this to work properly, but it does. This is on lossless albums in ALAC format, I can't comment on whether this will be the case with FLAC or MP3 as I don't use either of these formats.
Finally I get no audible artefacts whatsoever when skipping, pausing or un-pausing tracks, so again not having any of the issues cited by other posters, whether this is fw or hardware related remains to be seen,
In summary then, on a player purchased 21DEC from an eBay seller whom I believe is based in HK, I received a unit which was pre-loaded with fw version 1.1.4. When tested throughly with x2 FAT32 128GB cards containing all lossless ALAC files, I can find no issues whatsoever, including flawless gapless playback of mixed albums.
My final comment is that I am very fastidious with my file metadata - I have no idea if this is of any relevance.