For TTware datalog I prefer 40 col as the compressed font is harder to read and 40 is enough for the data that is logged. To save paper change the line feed to off (dip sw-1, no4 OFF) and you will cut paper consumption in half. Paperrollsplus.com has several varieties of thermal paper that will work for good prices.
Datalog for SST paper use is also reduced (33%) by the line feed setting but will skip one line (instead of two) afer each printed line.