The common denominator remains the old StuffIt 1.5.1 format, since all of the compression programs can expand 1.5.1 files (this is why we included a StuffIt 1.5.1 file in the decompression tests). Not surprisingly, StuffIt Classic and StuffIt Deluxe can also create 1.5.1 archives, unlike the others. However, most of the online services, including the Internet file servers, have adopted a policy of allowing any format if a free decompressor is available. America Online is the major holdout, since it prefers uploads in StuffIt 1.5.1 format and only allows other formats if the files are self-extracting archives.
Yet another program will try its hand at the competition soon, when Alysis Software releases SuperDisk!, which is designed to compete with DiskDoubler and provide transparent compression and expansion of files. However, SuperDisk! will also go after the other programs by creating smaller archives in less time and by including the ability to create self-extracting archives. It should ship in a month or so. If that's not enough for you, a shareware program recently appeared on the scene to compete with DiskDoubler. AutoSqueeze from Dawson Dean transparently compresses and expands files or folders (and the files in them) whose name ends with the word "compressed." It's $20 shareware and works quite well, though in our informal tests it isn't as fast as DiskDoubler nor does it compress the files as much. A friend was recently bemoaning the number of choices in the compression field. "It all used to be so easy," he complained. "Everyone loved StuffIt and thought Ray Lau was a god. Now we've got a ton of formats to deal with and trade-offs wherever you look." There is something to be said for simplicity, but we're unlikely to ever see it again in the compression field.
The bottom line? It's a toss-up. I'll be using all three - StuffIt Deluxe for the Magic Menus and mail hooks (not to mention JPEG compression for Photoshop documents!), Compact Pro for my uploading and downloading, and DiskDoubler to compress all the infrequently-used files on my hard disk (definitely cheaper than buying another hard disk). And by the way, don't try these tests at home - compressing files for eight hours with a stopwatch is not in my "Top 10 Things To Do" list.