Nevermind 20th Anniversary

I am having a dilemma right now about whether or not to buy the 20th anniversary "Nevermind" reissue. I obviously already own and love the game changing Nevermind, but this one will include early editions of "Lithium" and "In Bloom" recorded in a studio in Wisconsin before Nirvana was Nirvana.  Apparently the reissue will also include rehearsals of "Smells Like Teen Spirit" recorded on Cobian's boombox.  The question is do I need all this?  One thing, many of the recording are sans David Grohl.  At the time of the Wisconsin recordings Chad Channing was still the drummer.  But Grohl was still pretty involved with putting this all together.  So what do you think?  Is it worth the money?