Aha, something was tickling my memory, so I checked and Blackie can save a color original as well.I also like Argentum because even though it shoots in b/w it can save a color capture at the same time. If I decide I'm not happy with the b/w mix I chose in Argentum, I can take the color image into Lightroom Mobile or Pixelmator Photo and redo the b/w conversion.
EDIT: And a little more poking around shows that Argentum can save a b/w, a color, and a raw image all at the same time. Apologies for hijacking this Hipsta thread.