Mark has answered this question pretty well. From my perspective it's
the discovery and "work together" part (chat, etc) of Tow Truck which
is most worth exploring in the short term (and possibly adopting).
I'm (personally) less concerned with how the editing gets done (for
initial demo purposes at least) than with what we learn about having
groups of editors find each other, communicate, and collaborate. Tow
Truck has a pluggable system for editor components; I expect the first
work will be done with whichever editor is easiest to plug in.
IIRC Tow Truck has an existing editor for <textarea>s, so the first
demo might well use the existing PHP form-based editor. Once the
basics are done, and assuming we like the collaborative model and
mechanism in the basic demo, then yes it would be interesting to see
different editor plugin options. I suspect Mark and I would work on
hooking up VE next, because we are masochists.