I was BC skiing with my long time Dynafit using friend the other day. On one section he chose different route up a steep narrow ridge than I, and found himself on a very steep section. Locking the heel and side stepping was his only safe option. Once he gained that section he needed to switch back into the tour mode from ski mode. In my G3 Onyx review , I mentioned that one of the primary toted benefits of the Onyx is that you can switch from ski to tour mode without releasing out of the binding completely (staying in the toe portion of the binding) . Since the toe part of the binding is tricky to enter, keeping the toe attached while while switching between ski/tour modes is a plus, especially on dicey terrain.
I thought it was common knowledge that you can pop the heel out (ski to tour) of dynafit bindings if you did not have ski brake equipped bindings; I guess not. So here is a little video for you'all. Watch, learn, practice.