I posted this on another site when someone asked about the 25-50 vs 20-60.
"I had that exact question last summer. A buddy and I came across a good deal on some 65mm bodies but weren't sure which eye piece to get. So, he ordered the 25-50 and I ordered the 20-60 and we compared them side by side. The 25-50 has a wider field of view, no doubt. But eye placement with the 25-50 just seemed so much more finicky. If we didn't have our eye in just the right spot we would both experience the kidney bean or blackout effect. And, the higher the magnification went, the more finicky eye placement became. We both thought the wider field of view was nice, but not enough to put up with the eye placement issue. I kept my eye piece and he sent his 25-50 back and ordered the 20-60."