I agree with the first post 100%. I think Araxis Merge is a better comparison and merge utility.
I actually used and licensed Beyond Compare prior to using Araxis Merge, but it has a few short comings that I believe is handled better in Araxis Merge. After evaluating Merge for a couple of weeks, I licensed it and use it more than Beyond Compare.
Here's my main reason why:
Araxis Merge does not reformat the appearance of files being compared. Beyond Compare will add spacing between lines to match lines it believes are the same for two files being compared. The reality is that it's not always correct in its assumptions, and I end up looking at a mess. I prefer Merge's way of handling this with synch lines. In addition, when the assumptions for matched lines are indeed incorrect, manually aligning in Beyond Compare is not intuitive at all.
We all know what else Merge offers that BC does not, so I won't bother repeating it.