Thanks for the responses. I have used your profiles in Photoshop but recently have been using Hahnemuhle Photo Rag Baryta which you haven't got around to yet. But many thanks for the time and effort you have put into these.
The main issue is the gamma of the data that gets send to the ABW driver. LR will send ProPhoto RGB data to the driver, which is gamma 1.8. However, the ABW driver assumes sRGB gamma data, which is ... err, ~2.2. So images normally printed from LR to the ABW driver will appear too dark, especially in the midtones, when used with the ABW driver default of Tone = Darker.
One solution is to experiment with the Tone settings (try Normal or Light instead). But this is sort of hit & miss.
Another solution is to use the one Tom indicated above, i.e., try the various ABW profiles that I've built for various papers (link given above). This completely resolves the gamma issue.