I do like XP2 with natural light (and it can be printed on B&W paper just like any true B&W film with beautiful results -- just as well as Portra). However, I do also LOVE Tri-X for this same purpose -- and for an added benefit: if your light is low and you need a faster shutter speed, you can push it with excellent results. This can be a great advantage, and it's why I keep several rolls in my camera bag for every session.