Thanks very much for all the info, and the Nomad pic.
It was mainly an availability thing - I checked with Thorn and there are currently no Audax frames, but they have the Long Club Tour. I don't really have a lot of experience with different styles of bikes, and touring bikes in particular (my bikes tend to be unusual bikes such as fixed wheel, Moultons and recumbents etc).
I don't have any current bikes I could copy the geometry from. I do have some notes from previous bikes, so I think the Long would work, as I'm quite adaptable, but it might not be optimal, but that could be the same for any bike I buy. Also, because it's already built up I'd need to change handlebars, stem, bar tape, brake levers, shifters, cables, and maybe the transmission and brake calipers if changing to drop bars, so it might not be an ideal starting point. On the other hand, I may find the straight bars with bar ends are fine, especially if I can set the bike up with more of a forward leaning position (for the headwinds Mick mentioned).
Most of my riding is on the open road, so perhaps the stable steering wouldn't be too bad. However, I don't mind quicker steering bikes such as Bromptons (or my old track bike which could be steered 'from the front'). I had a Kona Jake-The-Snake which, with heavy tyres, always felt a bit ponderous.