Knew I should have finished fettling first, but I did say that things were in the wrong place
After spending ages carefully setting up the drivetrain (never had built up an SRAM roadbike before) I rushed the ancillaries to get the light to send off a pic to a mate who'd helped picking up a few parts.
Yes, the saddle was a good inch and a half too low, and too far forwards. The bar height roughly matches my Audax bike as a starting point. It's easier to move the bars down later or chop off a bit more steerer than to move them up! The bars were angled a bit far skywards.
The one thing I'm not sure about is the white bar tape. The (heavily discounted) groupset came with white hoods, so after initially thinking I'd just get black replacements (about a tenner for the genuine ones) I thought I'd try white bar tape too, to match the white decals and seat post. It looks better in real life than in the photo, but I may well move to black when they get too grubby as I'm not convinced it's right.
As for the wheels, I did spend some time thinking about them - but "sexier" looking wheels wouldn't be as comfortable or as robust. I'm intending doing some serious miles on this bike and I'm not of racing snake build so I'd be constantly worried going for anything with fewer spokes or lighter weight. That's also one of the reasons why I didn't go for an off-the-shelf Roubaix - I'd have wanted to immediately replace the wheels and saddle, which pushed the cost to close to this build.