Nememo - Well I tried again, using image from your link, created boot image usung rufus (only difference is 16k size sections default instead of 4k as newer rufus). used gpt and fat32.
Starts, but fails eventually saying required partition is not available. Same as my image.
Wiped mmc and did same, same error.
I have no idea why it does not work.
My concern is that people may think they ate safe going to 10 but if things go pearshaped they cannot recover.
Macrium works fine, so a backup method works for Linx 8 (others have confirmed this) but I cannot say for 7/10 but do not see any reason for it not to work.
In fact, as Macrium will insttall as a dual boot system, it might be easier from 7 as I seek to remember you can't get to bios if windows is not working?