Reading Paul's and Zero's discussion/debate about MS made me think about it, when i never really gave that a good though.

Although all Uchiha's have the potential to awaken MS, I can't believe that all of them get Amaterasu and Tsukuyomi, and ill explain my point of view.

The MS techniques that we know for each MS:
Sishui - Kotoamatsukami
Itachi - Amaterasu and Tsukuyomi
Sasuke - Amaterasu and Tsukuyomi (been passed down to him by Itachi).
Tobi/Kakashi - Both eyes have space-time tecnhiques, although on diferent levels, but both are Kamui's.
Madara - ???

So, every Uchiha has diferent MS techs, the exception beeing Itachi and Sasuke, but the second was gifted the first's techs.
Not only that but every Uchiha has a diferent MS eye pattern, if they were to have the exact same techniques, diferent eye patterns wouldn't be necessary or even logical to be "invented", only a general pattern like the normal sharigan with tomoes, witch makes logic to the fact that diferent MS eyes have different techs.

Witch doesnt mean that Susanoo can't be reached, i would guess that Susanoo is more likely reached by a certain power level than MS techs in both eyes, since we have read and see that the more the user gets stronger, the more "evolved" or complete the Susanoo gets.

Also, a side note to the reference on Harashirama's arm looking burned, it doesnt really implie amaterasu, because all uchiha's have an afinity to Katon, so even "regular" fire techs performed by a strong opponent would be great counters to mokuton.