Can you please be specific about both of these statements about DiffMerge? How is each app better?
The best way to find out is just to try both of them yourself, and use them for your needs, and see how the two compare. DiffMerge is free, and you can use a trial of Kaleidoscope.
Now, the one missing feature of DiffMerge that I would find extremely helpful would be the ability to edit text on both sides of the panel, similar to how WinDiff allows you to. DiffMerge only lets you edit on the right hand side. See
here for info. So if you want to make a small change to the file on the left, you have to reload the diff and swap the two files - extremely annoying.
Other than that, I really like everything it does, especially the way it highlights the differences and lets you edit the right hand file. It makes merging different versions (with custom changes, not just keep left/keep right) very easy.