Regarding long exposures under dim lighting, you will find that under certain circumstances, like for instance dimly lit daylight, that paper negatives can provide shorter exposure times than sheet film, due to paper's lack of reciprocity failure.

Conversely, working under artificial lighting with sheet film is typically better, due to paper's lack of sensitivity to the longer wavelengths. Since I work almost exclusively with graded paper negatives, my still - life work is done in the daytime using indirect north-facing window light, which at least is of a color usable for paper.

-Joe