Out of interest, do you have a good way to compare two parts of the same file using vimdiff without creating two files? Say a huge xml file with two nearly identical <parts></parts>?

I've actually never used a visual diff tool. Usually I just search the file for ">>>>>>>>>".

Maybe I should check it out.

If you are into this stuff, Araxis Merge is also worthy of consideration. It does a better job of char-by-char diffs than p4merge, and will recalculate the diffs after you manually edit the result.

The (old-ish) version I used had only 3 panes, though, making p4merge superior for 3-way merges. p4merge was easier to use from the keyboard, too. But for ordinary merges, I much preferred Araxis.

I've been happy with BeyondCompare. Reasonably priced, does 3-way merges, configurable with many version control systems. Now with Linux & Windows versions (but not a OS X version yet)