Quote: Any suggestions at how far beyond the camera's suggestions I should go?
The last one (1 sec) looks a bit blown to me but the 1/4 sec isn't really exposed enough ... somewhere in between, then add a bit of contrast after converting to monochrome, I reckon. Other people may well have different opinions; there seems to be something of a fashion for blowing out the highlights with IR shots, which may be connected to the operation of the histogram on the preview screen when there is a signal only on the red channel.