I feel like wearing the company sold brands is being dishonest. While I cannot respond as an instructor, as a student I look to my instructors for honest opinions and direction, and I think by buying only what the LDS sells you are keeping your students from being fully informed.
If you can't give unbiased opinions about gear, regardless of what you sell, and have a discussion about pros and cons with a student Im not sure you should be an instructor. IMHO it destroys the honest relationship that should be formed between instructor and student. Now, if a shop wants to give you uber discounts, and you HONESTLY love the gear and use if yourself, then that is different. BUT, if you use the gear ONLY because your shop sells it, you are just a marketing tool and not truly dedicated to your student.
Im sure this will get some people upset, but this is a personal opinion of a student, so please understand my bias as well.