We have a Powrtouch on our twin axle, Brilliant with no probs at all. Have had both the other popular ones and the Powrtouch is the best.
Bear in mind that twin axles are much easier to reverse than single and I have found I do not use the mover very often but still wouldn't be without it on the odd pitch.
Make sure its fitted to the back wheels and the jockey wheel is wound right up to lift the weight off the front wheels. Works okay but not as smooth as the single axle movers.
We have the Rhyno Mover and are delighted with it. However, as far as I know the only company who specifically make a mover with power to all wheels on twin axle vans is Reich,. However, this is both heavy and expensive. To the best of my knowledge none of the others will not perform as well on a twin axle van as they do on a single, due in part to the increased weight as well as onse set of wheels tending to 'drag'