That is very nice. We made the gmt logo module so that users can place whatever size they want, with a few options for labeling. This is in contrast to the timestamp which actually sues a tiny bit-mapped image for the black/white part and would not do well if scaled up due to a larger font size. While I am not bothered by FONT_LOGO being allowed to change the font type (size and color are fixed), I am not sure this buys anyone any happiness, so perhaps it would be simplest to retire that setting.