Blood Demon Angels.
We already know that becoming an angel will be affected by your previous demon sub-race e.g. night bonuses of Shadow Demons. But the details regarding many of these carried over treights are little to none. I personally intend to play as a Blood Demon seeing as I have no idea how much they've planned for this I would like to make a suggestion. (Now I don't know too much about how the Blood Demons, or angels will work so take this with a grain of salt.)
I think that it would be an interesting concept for Blood Demons who redeem themselves and become angels to have a concept similar to "Sol Vampires" or "Reverse Vampires." The way this works is that reverse Vampires consume chlorophyll from plants as apposed to blood. There's more info about the general "lore" here
Overall I think it's an intreiging concept and could help with the idea that angels are good alligned, but Blood Demons drink blood.
@nines they said that angles will get new skin, new racials and new attribute mods.
@finland they've confirmed that "both your look and your attribute bonuses/maluses as an Angel will depend on the family (sub-race) of your character. Same for Beastmen -> Abominations. Other unique abilities of the original sub-race (e.g. night bonuses for a Shadow Demon) might persist after the transformation too " which means that at least some of the traits will be changed depending on sub-race. I'm just throwing this out as an idea for Blood Demons when they become angels.