I've personally not had any experience of them Paul but many caravanners say that any type of mover fitted to the jockey wheel has only limited efficiency due to lack of traction. Which type have you got?
I would imagine that for use at home, on a driveway or similar, it'll probably prove its worth in the long run. Perhaps it would be best to test its efficiency, especially on grass and uneven ground before fitting it instead of your existing jock or taking it with you on your trips.
For the several years we've had our Troll, because we've not got a mover fitted, we've rarely got into a situation where we could really have done with one. We always ensure before pitching that it will be easy to get the van out again. On the few occasions where we have been caught out, there's always been a couple of hardy folk around to give us a push However, we do carry a hand winch just in case.
Randa