The curious thing about the disciples of Reb Israel Salanter is not just that they came out with different approaches all based on Musar but that each presented their approach as The Right One. In the newer Musar approach most of the aspects that were unique to the Musar movement all got forgotten.
I can not tell what to think of this. After all Musar represents different points of view.
That is even if you go back to the original set of Medieval books some go more with the Rambam Saadia Gaon approach and others with the Ramban [Nachmanides]. Later when Kabalah got thrown in, all the more so the approaches begin to differ,
Once you get to the great Musar yeshivas, Mir, Slobadka, Navardok, Kelm, it gets even more diverse.
What seems to have happened is people settled on one basic approach that they found was workable--Musar and Gemara. And with that every individual will find in Musar what he or she needs to learn from it. That is about the best I could figure out from what I saw. This Musar and Gemara approach also makes sense to me.
Or at least it is the approach that I hope to stick with. [My own approach is more or less this: Gemara Musar, Rav Shach's Avi Ezri, Physics, Math. That is based on the more rational Rambam Saadia Gaon approach to Torah.]
In a nut shell it is hard to explain why Rav Shach's Avi Ezri is so important but basically it is the need to understand Torah beyond extra forms. One needs to get to the essence of Torah.
But the place for Torah learning from what I can tell is in a Litvak yeshiva where you find the spirit of Torah. Maybe Torah VeDaat or Chaim Berlin or some authentic yeshiva. But no fakes. The fake and phony yeshivas destroy the spirit of Torah and one must run from them.