there are many problems with this theory that you obviousley havent seen as this was your first post... this discussion has been ongoing for the last couple chapters.
1st, danzou has problems with his arm and leg, madara/tobi does not
2nd, danzou has spent a lot of time and effort on ruling konoha while madara was once the mizukage. (he couldnt rule two nations at war with eachother)
3rd, danzou wants sasuke dead, madara wants him alive. madara wouldnt kill him as he wants to sync him with gedo mazo (effectively making him a jinchuriiki)
4th, madara needs the kyuubi for gedo mazo, if he was danzo he could have easily kidnapped naruto
thats all i can think of for now but basically although they are very similiar in appearance they have conflicting interests
1. Purely speculation on my behalf, but judging by tobi/madara's techniques (it's like his body isn't there), maybe tobi is one of madara's techniques and danzo is actually the madara using that technique. That's the difference in their physical attributes (arm/leg). Not to mention Danzo could just be putting on a show.
2. Remember the story of "the valley of the end"? Madara was defeated for the title of Hokage. He wanted to be the hokage, but he was defeated and because of that, he became the Mizukage to further his ambitions. If his ambition is to rule the world then he'd have to wag the dog until he takes his seat at the head of all the nations.
3. If Danzo is madara, then he'll know that Sasuke won't be captured or killed easily. He probably issued the execution order to get Naruto worked up so that he would leave the village and could be captured without Danzo/Madara giving himself away. Itachi also said that Madara is a shell of his former self, meaning that his body isn't suitable to fuse with gedo mazo. Why would he want to give all the power to sasuke, whom he can't control completely? Madara probably plans on stealing his eyes or his body or something creepy like that.
4. If Danzo and ROOT kidnapped Naruto, he would be giving up his chance to manipulate konoha because he would be found out rather quickly. Especially with kakashi sticking his nose in everything.
Then again, Danzo could also be Uchiha Fugaku. It sounds like Danzo's brutal tactics to have his own son destroy the entire clan, even get cut up himself, in order to conceal himself in the Konoha government. That would explain Danzo's scars and lame appendages. He also bears a slight resemblance to Fugaku. Take a look at Naruto Manga 400 page three. If he's an Uchiha, then he's definately kahooting with Madara.
