Best of luck. In addition to shoulders, I would have a sense of what you want for length and button config as I've seen varying results from Chan on those parameters.
Just one general note in praise of Chan: they are extremely consistent. I've ordered 9 jackets on my current pattern, never with fittings, and with one small exception all are spot on identical in all key aspects - front/back balance, shoulder line and width, sleeve pitch, chest shape, waist suppression, lapels, length, quarters, and buttoning point. The one exception is a light grey suit I ordered that has slightly more closed quarters than the others. Whatever method they use for patterning/cutting is remarkably precise. I've been tempted to try out other tailors but can't be bothered with the hassle of the tailoring process. I've assembled a pretty good collection of cloth swatches at home, so ordering a new suit is as simple as emailing them a cloth number, specifying lining and button colors, confirming credit card details, and waiting 2 months.
I've found Chan fairly consistent on the big points but often with small variations that require correction. I've had pants cut a bit large or long, slight differences in the openness of quarters, and once a fair amount of extra padding added to a jacket's shoulders. Having said that, I think being in HK leads to a better and more consistent product, and I try to do fittings whenever possible. For a DB, I would definitely want to do fittings.