I would dissent here because I believe Quran is superior to the thought of any scholar. I am not saying that the model you said is invalid, that is also valid as far as Quranic advice is concerned. However, the above Iranian model is also perfect as far as the advice of "mutual consultation" in Quran is concerned, because not anybody can run for president. If you notice carefully, the Guardian Council, which consists of experts and highly knowledgable individuals, selects who can run for President. it is not like, for example, pakistan where any rich guy can run for president.
As far as democracy is concerned, it is very much compatible with Islam's advice of "mutual consultation". The Iranian model fits perfectly. The model you suggested also fits. In fact, Europe adopted these values - freedom of speech, democracy, human rights, women's rights, equal rights, parliament etc all of these were imported from Quranic values. We would be surprised how compatible these western values are with the Quran, if we just study the Quran ourself without listening to any mullah.
This is why Ahmedinejad is a middle class individual, who holds PhD and served as a professor and lecturer in university... Is there such a qualified individual as president in most other muslim country?