I've recently had a few things made by WW Chan. They started by copying the first DB suit I had made at A&S, some 15 years ago.
In spite of that, the suits could not be confused with each other. Chan likes square-ish shoulders; even after I had them take out half of the padding, it's still a much less relaxed look. And while they do a very elegant peak lapel on morning coats, etc., for DB they insist on straight edges and more or less horizontal notches. No idea why. The SB jacket looks fantastic in a somewhat generic American/International sort of way. Excellent proportions. In both cases, good results if not especially English.
For fit, they are excellent in parts. They copied the belted trousers from London, but snipped in about one inch of girth from the thighs. The end result is both comfortable and elegant. On jackets, they like clean. I need a lot of drape in the back to have enough room to move, and might just get almost enough next round, but it has meant some negotiations. Anyway, I've had the first SB jacket altered and it nearly fits well. I have a subsequent suit that needs a trip to the same alterations shop, and might do even better as they did add a little more cloth at my insistence. Oddly, the original DB suit jacket fits much better-- perhaps the buttoned front keeps the arm scye in the correct spot, where SB jackets need a bit more help in moving it forward. I had a dinner suit made, and found it very comfortable to use while playing a concert last summer. No small feat for a fully buttoned, ventless, DB jacket while seated.
The construction is an interesting paradox. Light weight canvas, but a little stiffer, and crumples less gracefully than its London counterparts. I wore a light-weight SB sport jacket around on a trip last week, and it looks a tad tired.
For trousers, you get the most obvious deficit. Waistband is nowhere near Savile Row in quality, and the belt loops look cheap. Kilgour's Shanghai suits had some of the same problems. Interestingly, like many HK houses, Chan will put rubber on the inside of the waistband, which does help unbelted trousers stay up. So that's one reason to use that suit for air travel where security is an issue. Otherwise, for the same money you can get way better-quality pents from NsM.
Final verdict-- trousers fit beautifully but aren't as much fun to put on and take off. May still use them as a source for this.
SB jackets may be useful for summer wear, if they do as they promise with more drape around the shoulder blades. No idea how their construction would work on winter wear-- if the light innards would be helped by the heavier cloth, or would sabotage the whole project. (Simon Winchester wrote about this problem.) In any case, potentially useful for business suits to wear hard. DB summer suits would be the obvious synthesis of their strengths, if only (a) I didn't already have a lot of them, (b) summer wear often rewards the softer A&S style, and (c) I'm less likely to want to have DB for schlepping around during 9 to 5 in hot weather.
One additional complication is that for just a little more in cost, Whitcomb and Shaftesbury now has a bespoke program with Indian labo(u)r that, if it produces a suit with English construction, may end up being better value. We shall see.