Ok, it has been a while but my A9 is doing well. I worked out a few issues with other components (Ultegra 8020 not shifting that well with the 11-speed Durace chain until I replaced the chain for a 12 speed Durace/9100 model), handlebar tape and a wider/shorter saddle.
It's a lovely bike now. The XL model works for me (1.96cm) running 175cm cranks. Seatpost has plenty of room left still. Pretty stiff where I want it to be, but - helped by the 32c tires - plenty compliant, am using the standard headset, and there is no play. Having this bike now makes me a little more observant when I see other brand-name bikes and I started to notice a few look alikes. i.e. Polygon Helios looks almost identical, to some of the Scott models - it might just be a popular shape?
Added a few pics for the interested ones just after build, before any fine-tuning.