I kinda view Pro as that off switch. There is still some prioritisation going though, so it's not completely unmanaged.
The view of one potential customer (i.e. me) is that Plusnet would me more attractive (to me) were there to be an off switch (as opposed to the re-prioritisation switch) which removes the management entirely.
I do understand though that it is not entirely about managing traffic for the customers' benefit, but also managing load across your network as a whole.
Oliver.