I have DB and SB suits from both.
While he is obviously of A&S background, what Edwin has done for me at Steed has a very different feel when worn, and a moderately (but noticeably) different appearance. Steed's trousers for me are more voluminous than what A&S does. Edwin also gives more space through the chest on all jackets, somewhat fatter lapels on SB, and altogether different front panels on DB, which are fairly flat and give oodles of space in the chest. Also for some reason, Ed places breast pockets (inside and out) lower than what I get from A&S. Warning: Spoiler! (Click to show)
A&S DB clings more to my chest even when unbuttoned. I don't know if that is an issue of cut, pressing, sizing, or small personal judgments as it's all being put together, but if the Steed DB feels a bit like a cape, some of the A&S jackets look like a sports bra before I put it on. Even though the basic measurements are not all that different.
Bear in mind that A&S has more than one cutter, so what I got started with John Hitchcock may not be exactly what you get when you walk in the door. Steed is based on Edwin (and maybe now his son). Hitchcock has much more of my build, while Edwin is rail-thin. So perhaps they brought different personal experiences of good tailoring to my body. Communication can also be more or less effective depending on who the client is, and that will affect how things evolve.
To complicate things further, Edwin's first set of my measurements were made when I weighed more than I do today (and when I started with A&S before that). So the image he had of what I needed may have come from different raw material. And there may simply be someone at A&S whose style points more to Steed than Hitchcock. All reasons to avoid drawing too many trend lines through one datapoint.
Thanks, Concordia. That echoes what I've heard from a friend who also has both -- although Edwin obviously comes from an A&S tradition, Steed and A&S offer different things.
I've been wanting to try A&S but wasn't sure if it made sense since I already use Steed. I'll see when they're in San Francisco next then.