I think some of the issues AMC has with SDPs may have more to do with the vendor than the concept. Last year at AIS, the instructors said something to the effect that the contractor had lapsed in its duties and was not updating the terrain/obstacle database as was required. Never heard Jeppesen's side of the story, but many in the AF have been weary of Jepp products for a while. (seem to work fine for civil operators tho ??) Interestingly, in the -135 community, we have been approved to use SDPs, but currently lack all engines operating performance data, making any advantage gained bu using an SDP effectively moot. I'm afraid that much of our community has blown off a potentially effective tool as a result.