My own two cents?
I'd say no to this.
I'd say that while pointing out that I consider myself a devoted, though poor, servant of the Blessed Virgin Mary, and I usually say more than one Rosary per day. I'd say that while acknowledging the many, many graces I have received through the intercession of the Blessed Virgin Mary, and knowing that if I have a place in Heaven, it may be only due to her prayers for me now and at the hour of my death, as my merits are so few, my sins are so great.
My reason is a simple one. Mary only is who she is because of her Son, the Redeemer. She is the Immaculate Conception because of the death of her Son on the Cross, a miracle made possible only through the divine foreknowledge of God.
I think the title, no matter how narrowly defined, will be misused by every critic of the Church to the detriment of the salvation of souls. We will be accused of elevating Mary to the Godhead, no matter how carefully we explain it.
It will also add a barrier to unification with the Orthodox, with whom there are so few barriers remaining.
Better to leave the mystery as a mystery in some cases; as it was not revealed in Scripture or held definitively in the first twenty centuries of the Church, I do not see the need to define it now.
I will, of course, accept whatever the Holy Father says, as I accept his authority and that of the Church as being binding on all Christians.