When Rashi says "מום שבך אל תאמר לחברך" what he means is that if, for example, a person is corpulent, he wouldn't call his friend fat. It only calls attention to his own issue. So the pasuk is [as we explained] giving us guidance how not to afflict the Ger. You were Geirim in Mitzrayim so don't "chepper" him that he is a Ger, calling attention to your own problem. But more than that. When you were in Egypt, you weren't inferior. On the contrary - you were far superior to your evil Masters. [Example - The Nazis were infinitely inferior to the the Jews]. So just as you were Geirim and not inferior, so are Geirim not inferior in any way.
Now we can answer the question of the Alshich on the pasuk "כי גרים הייתם בארץ מצרים". He asked that these are two fundamentally different types of being a stranger. How can we compare a convert and our status as Geirim in Mitzrayim? Same word but totally different. The answer is that the common denominator is that neither type of Ger is inferior and THAT is the point of the pasuk.
Then the pasuk concludes: "אני ה' א-להיכם" - meaning, I am EQUALLY your G-d. What is the value of a person if not for his importance in the eyes of Hashem. So the pasuk is asserting that a Ger is equally valuable as a Jew in G-d's eyes, so how can you cause him emotional pain??! This again guides us with the correct attitude that will prevent us from afflicting the Ger.
