Tracrig,
I contemplated getting the ScangaugeD for our Itasca Horizon 36GD with the 330 CAT when I couldn't read the Medallion Information Center LCD screen due to it being so dark. The Scangauge does just about all of what the Medallion factory info center does and, a bit more. In reading the specs, it, as you've seen, "claims" to display Horse power.
Well, I'm not any form of an expert here, especially on CAT engines but, correct me if I'm wrong here but, I'm always under the impression that in order to get any form of a HP reading, one needs a dyno to do that. I've talked with a few on that and, most agree that the Scangauge really doesn't have the ability to correctly read or, produce HP readings accurately. I could certainly be way off here and, maybe some of the users can figure out a way for it to produce an accurate reading, if it's possible that is.
But, I chose to order up the newer version of the Medallion Info Screen and see how it does. Good luck.
Scott