First, if freedom implies choice, slavery implies the absence of choice. Hence, making a choice to transition out of slavery into freedom sounds contradictory. So, on logical grounds, your slogan sounds a bit off.
On historical grounds, the two words "slave" and "freedom" should be treated very carefully when juxtaposed in the way they are in your slogan. It may trigger, in many American readers at least, the collective memory of an atrocious practice. You don’t want that.