As I understand, MtoA will regenerate .tx files for each texture prior to rendering, if and only if the non-.tx version of the texture has changed. However, this process does not respect color-space changes (which are included in the .tx when it's created).
Further, the Tx Manager's "Create .tx for selected" also ignores this change. Every time I change the color space of an image I must close maya, delete the .tx files, and restart it. What work-around is there for this?