While I have never used Efke 25, I have experience with one of the rebrands of the material identified herein as JandC 200. In my experience and the experience of many other photographers the material identified as JandC 200, while a nice film, has the limitations of building a density range of about 1.75 or slightly above. While, when one views, the data that JandC provides it shows that Efke 25 is capable of a DR exceeding 3.0.
I am not surprised by Steve Sherman's comments to this thread for several reasons. The first is that, on the basis of previous observations of his attitude and responses, he has an almost antagonistic response to anyone who avails themselves of objective knowledge of materials. Second he seems to parrot the words of many of the DBI photographers who have chosen to follow the Smith approach to photography.
The unfortunate thing is that this approach does not lead to a good knowledge of materials and their characteristics. Certainly not sufficient to intelligently discuss the matters in sensitometric terms. For instance, JandC 200 will never build density range beyond gamma infinity no matter how long you expose it and how long you develop it. Gamma infinity for that material is what I expressed prior.
Efke 25 by the same token has far greater expansion potential...far better suited for the Azo printer provided you can live with the spectral response and the slow speed of the material. But then the person who does not avail themselves of the published characteristics of a material would not know that other then by trying the material under actual conditions. That would lead in many cases to wasted money and time testing materials that are not well suited to a given process.
Now on to my earlier comment about reducing development under reciprocity conditions. That is known and used by knowledgeable photographers who have grasp of their materials and who wish to arrive at consistancy in the density range of their camera negatives under varying conditions. By contrast, for those who are disciples of the windage and elevation school of sensitometry it makes little difference.
Now on the subject of the reciprocity compensations that Steve kindly provided and strongly suggested we use, I will acknowledge that they may work for certain films...but certainly not all films. In fact I would suggest that they may prove counter productive for certain applications. I would take those suggestions under advisement subject to my own testing of the materials that I choose to use. To do otherwise is irresponsible in my opinion.