ROL - last year I took my Ebony w a 6x9 holder with Efke 25, Pan F, and Efke 25 up behind Mineral
King for about a week in mostly wild weather (lots of rain & snow). The effective speed and capacity for detail was about the same for all three, but each with a very different characteristic curve. I dev all 3 in PMK. The Rollei was a bit disappointing in terms of deep shadow detail - a bit more of a toe than I like in a high country film. Pan F has a very short straight line, of course, but is nice in lower contrast settings like mist (there was plenty of that on the passes). I still have a fair amt of Efke 25 in the freezer, but it's very subject to light piping, so has to be loaded in deep shade; but it has a wonderful scale and can handle extreme contrast well. Don't know what I'll choose next time - maybe just stick to 4x5 and a film tent so I don't have this dilemma.