I was involved with a whole bunch of “Nuclear Promise” activities and the SDP was one of the more beneficial ones to adopt from a consultant point of view. Working directly for the utility, I’m not sure the SDP means as much with the exception of not having to do thorough implementation details.
In the south, where I’m most involved, most utilities have fully adopted the SDP. VC Summer was one of the last due to the Dominion/SCANA merger.
Like you alluded to, most sites defer to plant specific databases and forms for things like ADLs, Equipment Lists, FP forms, etc.