First of all "Shifu" is a term used only when one has been "adopted" into the martial family. Just because you train with someone does not necessarily mean you are their disciple. (for more on discipleship ceremonies in the martial arts visit my website under articles) If you have not become a disciple and are forced to use the term "Shifu" you may want to inquire about such things.
Secondly if one were going to stick diligently to the Chinese language then use "laoshi" which is the proper term for teacher.
I believe it to be a bit conceded and strange if I must address a westerner, in the west, as I would an easterner in the east! "Mr." or "Sir" is proper and polite here in the US. Nothing wrong with those. I also like the BJJ term "professor" or "coach." To each their own I suppose.
Anywho.... here is a little snippet that I think you might get something out of. I do not agree with 100% of it, but in general I like what it has to say, and all one has to do is substitute "coach / teacher / professor" for "sifu."
What is a Sifu?
The relationship of a Sifu to a school is very difficult to explain, as it encompasses many varying aspects of life. The Sifu must flow through the student in many levels of communication and reach the corners of his life. A Sifu is a father and at times a mother, an advisor and a chastiser. A Sifu though different is the same as everyone else. He is human in a controlled way and deserves respect, for he has traveled long upon the way.
A Sifu should be a good teacher - by this is meant that he can convey the appropriate knowledge to the students at the correct time in the best manner, he must be able to see them and their problems impartially.
A Sifu shows no favor; indeed, as progression is attained he becomes harder on those who progress. He is kind but firm to the beginner on the path.
He advises in an appropriate manner on the inner spiritual aspects of the art, and is always a friendly ear that listens but is not moved. Many people are unable to see a Sifu properly as they tend to categorize him into a teacher or a friend. He is neither. He is both and more. He sees the student in a free way, unmoved by the external face or appearance, and he helps in the best way. If this is to be hard then he is so, to be soft, then he is soft, but always it is in the best manner for the students, for a Sifu’s heart is forever with them. Often a Sifu may test his students by taking views dramatically opposed to theirs and watching their reactions. He will never praise. Silence is the best praise. He will note what effects the student in and out of the school, how he acts to his friends, his family and his work and accordingly. He will put forward untruths to see if they are accepted say nothing when he should speak volumes; he is kind when there is no reason to be. He may be tyrannous or compassionate but through all these externals his heart is forever with them. He listens when they speak but can see the reasons for their speech, he is unmoved but can move. He is forever active even in a subdued way. He gives while others take and asks no rewards, sane proficiency of mind and body. He is sad, sometimes unhappy, let down and often abused, but he forever holds to the way, for that way is him.
Though outsides may change, the Sifu does not, for he can adapt at will completely, the inward ideals are always there.
He may be abused but he thanks in return, blamed or criticized, he persists. He persists when there is no reason to. That is why he is called Sifu.
On an average basis, it takes 2000 students to produce one good worthwhile Sifu.
If you have one - take care of him.