Okay, as far as I understand the question is whether loss, upon cessation of therapy, will be exaggerated and accelerated as to match the point it would have been if Propecia therapy had never begun. As far as I've understood to this point, loss will be slightly accelerated so that after a while, using the example of therapy beginning at age 20, ending at age 25, by the time you're 26 your hair is the roughly the same as it would've been either way.
As far as I understand, the reason is because the sensitivity to DHT of the follicles has been progressing all while your DHT production has been suppressed, so sensitivity is as high as it would have been if Propecia had never been used. It is this increasing sensitivity, not an increasing level of DHT in the scalp, that is theorized to make hairloss progress in the later years of Propecia therapy. Thus, loss and miniaturization is relatively more severe than it would have been if it were a gradual loss. Don't quote me on all this however, this is what I seem to have understood from what I've read.