I don't believe its possible to fully train and ride a horse using -R; the challenge is perhaps more of using the power of the +R created attitude to carry it through to ridden. For other horses though, gently building step by minute step means that although the exercise is -R, the reinforcement history means it is perceived in a +R way...if that makes sense?
One of the problems with the DVDs is that there's very little of the finished product - Hilary and I went to watch Alex in the US partly to address this. I wanted to know where I was headed!! It is difficult to show just how small the steps are when correctly worked through and I know that we want to see beginners but without the end point, it can seem that this is how it should look.
This is really rambling, sorry!
Great post! Please keep 'rambling'!!

Well worded about using the power of +R to carry through to helping the horse to perceive -R in a positive way. I am always trying to pin down my thoughts on this and what you've said is really helpful. I think that Alex using more and more -R in her work is maybe tied to this where there is such a strong history of +R, the -R is still a positive experience! That's how I want it to be with my horses!!
Yes I've seen some really nice end points. I guess I've just seen some rough beginnings but also I'm just not that wild about using that series of steps to get to that end point. But then that's also just a case of many roads to rome...??