@WoRG
I'll add my experience with forwarding 1.07 blood rings to 1.08:
Most of the time when I open the character file which has my 1.07 blood rings equipped, I get the error message you describe:
When I get this error, its either once or twice - for one or both rings.
However if I dismiss the errors by clicking yes, Atma still can load the character and it will not modify the rings permanently as you described (and I have auto save on). Moreover, I can continue to use atma normally - although I have not (and would not) dared to interact with the equipped rings in atma.
When I mouseover the rings after getting the load errors, I get the following incorrect stats:
But sometimes I can open the character without any loading errors and then I get a normal mouseover of the rings:
I decided to make some 1.08 greater safety boots and saw 2 strange things happen:
no change to RLVL edit: I reread the guide and understand this now
less than the minimum Fire Resistance than is possible with the recipe which should roll between 10-25% edit: @WoRG seems to have worked this out in Post #18 - shame on me!
I used a lvl 99 crafter and a 'stale' rune:
Since only 2 affixes are visible and there should be a minimum of 3 with a lvl 99 crafter and stale rune, I assume that the 3rd affix rolled Fire resistance and the final value was truncated down to 5%. Indeed see post #18
However, I have no idea why the RLVL was not changed, here you can see the RLVL of non-crafted myrmidon greaves