I just upgraded from 7.5.8 to 7.6.0 and everything seems to be running fine. But I did have a couple of glitches during the upgrade because either I interpreted the instructions incorrectly or they weren't clear (at least to me.
Under "Preparing the File" step 5. The doc says "Upload all files and directories ... except for ...". But then there is a subsection that says "Upload these;" and goes on to list specific items to upload and not upload. So as I was sequentially reading the instructions and read the instruction to upload all files and directories, I did just that. I uploaded everything - except the 3 items listed to not upload. Of course this didn't work. Luckily I had a backup of the old UBB installation directory and I restored it to my server and then just uploaded the individual directories and files listed. Perhaps it could be a little clearer and not say to upload ALL files and directories from the unzipped directory except for the ones noted.
I then checked all the permissions as noted in the install guide and made any changes as needed.
I then ran the upgrade.php script. Everything ran ok until it came to the language file section. I got error messages saying that the permission wouldn't allow the files to be updated. I looked at the Installation Guide and didn't see any permissions listed for the languages directory. So I changed the permissions for languages (Linux system) to 777. The upgrade then proceeded to end with no more errors. Should the language directory permissions be 777? I don't remember what it was before I changed it.
Other than above, the upgrade went well and my board looks good on mobile devices. Thank you for providing that update.
But like I said earlier, I may have missed something when reading the upgrade docs. But I thought I'd share my experience in case someone else has the same problems.