That is very good advice, regardless of the future choice of developer (does the underexposure/overdevlopment method need serious adjustments if working with Diafine ?). I'll probably have to sacrifice a couple of rolls to get things spot on, but I might start by rating film at 800, underexpose and develop it as for 1250 or 1600. Hopefully, that will give me medium contrast and medium detail in the shadows, as a starting point to tweak until satisfied. What I am dealing with is a mix of flat and low light , the latter due to weather and tall buildings bordering narrow streets. I need some detail in the shadows because the pavement is usually pretty dark in my city (wet asphalt) and people are typically wearing dark clothes. I'm rather tall, so I tend to tilt the camera downwards, and that makes the picture contain a lot dark areas, which I find not to be exactly eye-cathing. ( It might be useful to mention that I use a Sekonic L-208, and meter for a combination of light reflected from my hand and from pavement, which gives me a reasonable average, I think - slightly brighter human faces, making them stand out in the picture, and enough shadow detail, but by no means all possible detail )
So far, a lot of people seem to recommend DD-X but I'm also tempted by Diafine, which is reported to produce good results. I still have to choose one and learn using it, before experimenting with the other.