Since you said you're open to keeping both, I'd keep both as they're both stunning pieces (I'm also a little biased because I have the same so black mini reissue). The rainbow one looks amazing IMO (compared to some of the other rainbow ones that have been posted in this forum). I also love the chevron pattern in so black! I know I'm not helping much
Let us know what you end up deciding!
You also have the same so black mini?? Can you post pics/mod shots? I'd love to see more, I haven't seen as much of it on the forum!