This is an interesting thread to me from the standpoint of considering the work of an independent examiner a "business".  I tend to think of what I do as a "profession".  If you approach the argument from this view,  I think the basis of Marks' original post is correct.  I have a small company, myself and three other examiners.  Each of them have over twenty years of experience.  We also have a support staff of four who handle the daily miscellanea; recordings,document retrieval, billing, deliveries and the like.
Back in the seventies and early eighties when things were slow, (and we were smaller) we covered the entire state of Ohio.  Now, we are happy to cover the eight county area that we have expertise in, and refer our clients to professionals we know in other areas of the state when they need service.  I feel my clients are better served this way, as they are not paying me to have one of our examiners spent half their day in the car.
Rather than base my price structure on the competitive concepts of Fortune 500 companies, I prefer to base my prices the way that the local law firms do.  I bill at a higher rate than most of the others in this area because I give a better product and better support when things are complex.  I would be reluctant to get any larger, as I don't think I could give the personal attention to my clients on each job that I give now.
I guess this makes me self-employed, not a business owner, but I am happy with what I am doing and make a darn good living.  I think both approaches to our industry are valid, we just have to make a choice on which we prefer.
I quite agree with you that you should not allow one client to make or break you, it was something my father hammered into my head years ago.
I wish I could learn to post as succinctly as Mark.