I'm afraid my comments are going to continue to be scattershot and not organized.
Beppe's and paola's comfort with Aziz has me examining my reaction to him. Is my discomfort with him a product of Forster's prejudices or my own? I don't have the answer to this. To what extent are ethnic differences innate and to what extent learned? These are questions of particular interest to an American. As Americans, we (as James Baldwin among others have said) have much more in common with each other than any other nationality. And yet, many Americans feel influenced by their ethnic background--even though, as we become increasingly mongrelized, it becomes almost a matter of choice. Which strain do we choose?
OK, trying to get back on track here. It occurs to me that Aziz also has a "passage to India" when he chooses to leave British India to live in a native state, and in the process abandons science for more traditional medicine, which might be more in tune with his personality. The irony is that as a Muslim, he is also an outsider in a native state, while in Chandrapore he lived among a community of his co-religionists. Moreover, with hindsight (vouchsafed to Forster when he wrote the novel), we know he most likely has another passage ahead of him in roughly 25 years--a passage to Pakistan, at the time of partition.
I got sidetracked there.