I'm laughing at myself right now! I was sure--absolutely certain--this must be an old zombie post back from the grave. Didn't you consider this a couple of years ago?
So, my experience: When I was a new associate, I worked with a custom-suit maker. Many of my partners had suits made by the same outfit, so I thought it would be a good place to start. The suiting I had made was well-made and nice fabric. However, it was ultra conservative and ultra classic, even when I gave directions to make it otherwise. So, I had to adjust my expectations majorly. Ultimately, I found I got much better fit and value with J Crew suiting. I'm not one to give up easily, though, so I tried with two other, entirely unrelated, highly recommended sewists. Both a bust. It isn't that I think great sewist/taylors don't exist. I really do. I just think there are very few Diane G.s in our world.
I suggest taking a really good look at your colleagues who are having suits made by the tailor and weighing how cutting-edge fashionable they are. If they tend toward conservative clothes, I would approach with caution. What kind of direction will you give to ensure you get the fashion fit you are looking for? Will the tailor be able to break through their assumptions about good fit to make what you want, not what they think you should want?
Would it be possible to ask the tailor to adjust the fit of something that isn't quite right but is very close? If you are asking for major alterations (adjusting shoulder fit, for example), having someone who is accustomed to making from cloth is going to really be to your benefit.