As you say, It really is. I'm unsure if it's because I am playing on x64 client, but I don't believe that is the case.
I separated the mod into two folders, xxxx20 and xxxx22. I tested it in the big building once when talking to Soha and another when heading into the isolated quest line room to talk to the thief girl.
I did as you suggested and disabled xxxx22. When checkout Soha, her bra was still on, her body was very contrasted. Continuing onto the the isolated room, regardless whether either or both of the parts of the file was enabled, it will always yield a CTD.
Probably it's a regional difference thing, similar to Lyn using different base body. Regardless, this is tragic because Soha deserves better. =(