I do bikini wax where its just the sides with knickers on, but they remove everything for Brazilians. I have done friends (close ones) who want it done, but are mortified at the thought of kneeling on the couch with their bottoms in the air. The skill is not only in the waxing, but making them as comfortable and as unembarrassed as they can be when you do it.
I have tried keeping knickers on clients when they are terribly embarrassed, and also don't do around their bottom if they can't cope, but I have found that knickers really do slow up the process, and a little gentle persuasion does the trick. I did a lady the other day who has been having them done for years, and was amazed at the speed I did it, and was intrigued by the new wax (non strip) as she has never had this before!
Ultimately, you have to do what you are happy with, but it has taken me 12 years to get round to doing Brazilians, and I have to say I love doing them, and am now getting a reputation for doing them well!
Vic x