Could also create two Advanced Segments, one showing traffic only from Safari, the other showing all traffic except from Safari, then compare the metrics to see how the Safari traffic differs from that which is not Safari (assuming it does).
Overwriting (not provided) Keywords with Inferred Keywords in Google Analytics
4/4/2013 This post describes a method for overwriting the dreaded keyword (not provided) with the keyword which you have inferred that (not provided) represents.