The thing that makes me twitch about SPRs is a concern that they won't change when the underlying conditions which created their data sets change. This doesn't mean that humans are good at noticing that sort of thing, either. However, it's at least worth thinking about which approach is likely to overshoot worse when something surprising happens. Or whether there's some reason to think that the greater usual accuracy of SPRs leads to enough bigger reserves that the occasional overshoot problem (if such are worse than in a non-SPR system) is compensated for.