Surely the flap/gear speed limitation is more a function of the training environment though? In the event of a real fire you could exceed these without worrying too much about the outcome which would likely be less of a concern than not reaching the surface in one piece.
Another advantage of the low speed dive with flap is that hopefully you have a suitable landing site in mind which you are planning the descent towards. At some point a transition will be made from a spiral dive to a stable landing attitude which will be a little more manageable from a glide with flap at lower speed than a Vne spiral.