I concur and would myself be more interested if such a book were available. I would also give more focus to Star Wars if more time were given to the Sith. If a story line detailed the stories of Asajj Ventress or Darth Maul for instance.
I dont think that if they were to do something like this for the Sith it would go all the way back to Revan. My guess is it would start with Bane and his "Rule of Two" and go from there. But there have been planes on releasing a Darth Plagueis book, I had heard that it was "shelved" but I would bet we wont see a "Sith Textbook" Till we know more about the Sith that follow Darth Zannah.
George Lucas and Lucasfilm always focus on the more positive side of things. Even when EU stories focus on Sith or renegades of other sorts, there was always a redeeming quality to these characters. Therefore, I kind of doubt a dark side guide will happen.
I'm pretty sure if they were going to make a Sith book opposite to this one, they'd actually go farther back than Darth Bane. Much of the ideas that Darth Bane used in the books came from some of the much older Sith Lords. Much of the info in the Jedi vs. Sith Essential Guide to the Force predates the movies by over 5000 years. And yes, they're releasing the Darth Plagueis novel somewhere in 2012.
I think a Sith book could be vary cool and funny. Have tones of pages ripped out from Sith trying to keep the secrets for themselves, tons of laws other Sith put in saying never kill your master and you get a cookie, best ways to kick kittens, in dept arguments on the way of the Sith, and of course a History of the Sith and the Sith people. Yes, I know some of my remarks where just stupid, but felt like it was funny to say.
Personally I think a Sith book or something would work. I agree that they might not have ever kept a book like that, but they did keep holocrons so why not a book. Who knows I am sure they can work something out that will work, maybe something "written" by Palpatine useing various text and holocrons from Korriban.