The guidance is to only use an interim build if you encounter one of the specific bugs it fixes. Interim builds are subject to less rigourous regression testing and not generally recommended for deployment except in the case I noted.
Besides this being noted in the release notes, you may want to listen to TAC Security Podcast #31 which covered the ASA release strategy as part of talking about the ASA QA testing approach. The full guide for that podcast series is here.
For new builds right now we are mostly using either 9.1(2) or 9.1(3), both ED.
ASDM 7.1(4) is the best bet for all recent ASA software.
