And since the only content where secondary stats actually matter are savage and ultimate fights which are mostly single bosses, no spell speed on SMN it is.

Also a correction on RDM : although the second spell isn't casted, it still triggers the GCD (you can't cast for a while) so spell speed affects this as well (strip all ss you'll see 2.50, put some you'll see 2.48 or less). Please start to understand how GCD works.