Mike, you will be hard pressed to do much in the way of minus development with this film. That is why I use it in flat light and the 100 form 'most everything else. Where it really comes into its own are those scenes where there is flat light (as in two stops or so between high and low values) and no wind. There were a couple of shots posted recently of a locomotive in very dim lighting. This will show you what flat light and efke 25 is all about.
What it does do well is build contrast like mad, so be careful with development times. I would use pyrocat at 1:1:150 as a starting point and go from there. Rodinal at 1:100 would also be plenty quick. With tubes and minimal agitation, you will have better luck with contrast control. Really a great film for tonality once it is tamed, but don't bother with contrasty scenes until you have done a few film tests. I would use it in 4x5 to get a feel for it, then have fun with the bigger stuff. I think you'll enjoy it, just be careful with times and temperature. tim