I like Timo's thinking in this thread. It's clear that the Saucer must
have had some kind of rudimentary warp capacity, because we often saw it travelling at what was clearly a faster-than-impulse speed.
Truth be told, if the reasoning behind Saucer Sepper was that it would allow families to get away during battle situations while the drive section engaged the enemy, then it never made sense to me. Why put all the families in the section of the ship which had no warp drive? Wouldn't it make more sense to give the bit with the warp nacelles to the escaping families, while a souped up Saucer engages the enemy?