One advantage of trading mothers would be that you could have sex with her, your mother who was not really your mother but somebody else’s mother that you had traded with. I imagine this might appeal to some people. It might be an exciting idea to them. On the other hand, it would be equally true that someone, specifically the person you had traded with, could be having sex with your mother, your real mother that you traded away. I understand that this would be upsetting to some people. Although not to others. Unfortunately, the ideal sensibility for such a situation, a person who was excited at the thought of having sex with his newly acquired, not real mother but who was not at all upset by the idea of someone having sex with his recently traded away real mother, seems rare, if at all possible. The degree of excitement would likely be in direct proportion to the degree of upset.
Even if you did not want to have sex with your new mother, or if you included a no-having-sex-with-her policy in the trade to insure against being upset, there would still be advantages. You could hug her and curl up with her without any danger of the fear and revulsion that ordinarily comes from accidentally holding her breast in your hand for a moment, or from when, in extreme comfort or near sleep, she presses her bottom into your lap.
Travel through your house could be made easier in that the importance of closed doors during states of undress or copulation would be relaxed.
She would cook different things and, better or worse, a change is always nice. It wouldn't bother you the way she never finishes a sentence. She would be just like any other sad woman. It wouldn’t be your fault.
Another interesting thing would be that, legally, you could marry her, provided neither of you were married to other people at the time. You could marry her and still live together as mother and child. That would be interesting. Even with the no-having-sex-with-her policy in place.