I've been using Hex Fiend, and while pretty good and FOSS, it still lacks in some of the above (especially in UI). Looked at Synalyze It! and while it looks pretty much perfect with some nifty syntax ...
HexEdit is an open-source hexidecimal file editor for the Macintosh. Developer Lane Roathe indicates that a new version, 1.72, is ready for download on SourceForge. With HexEdit, programmers can edit ...