In most cases, the SQL is more than OK. The only time the database is under a lot of stress is when the server is loading, and that's hardly a cause for concern since nobody is playing. They're all nice features, except I don't think the databases will ever be big enough to actually kill the performance that much. The only reason I said something is because I want to be able to edit my DB via the thingy-ma-jigger-tool. Otherwise the selection and insertion is OK.
Considering in this pack, skills armors items are defined in XML files, not SQL so that much stress has already been removed. Considering I work every day with databases that contains 10's of millions of records that have 100+ columns and no foreign keys, I think it's ok.