From what I have read it is a worth while investment...they only draw back that I can see or have heard is storage. You lose most of the storage space for the LP tank. But I have also heard that they are make newer and better tanks that can be mounted better....well you get the idea. If it would be a worth while cost savings here in the USA, I know I would concider it, but since there are not that many places (at least not in the state I live in) that offers LP fill ups for vehicles I would be very limited on fuel stops.
I know that in the UK they offer all kinds of tax breaks for switching to LP or at least that is what I have read.