I just had an excellent experience with the general manager of Tourbillion, David Nobles.
He's not only quite informative of the watches he sells (and also the watches he doesn't sell in his shop), he also offered a purely unbiased opinion on all of the watches I was considering. I have no doubt that his opinion is genuine and that he would direct me to the right piece for the reasons I want the watch, not because he wants to make a sale.
Truly trustworthy, I recommend seeking David out if you're torn between multiple watches or would like an unbiased opinion.