Electric caravan brake controllers

I am in the process of rigging the Cruiser to tow a 'van and did a thread search to get some info on best type, worst type etc of electric brake controllers. It looks like the general opinion favours the Tekonsha Prodigy or Hayman Reece. A previous thread stated that in this posters view the electric brakes will tend to release rather than apply when in reverse. I would have thought this could be rather dangerous if backing down a steep hill i.e. no caravan braking. Does anyone know if this is true or not?

Thanks in advance

Cheers ob