All good info, and I appreciate the time to educate. Bringing up the UNIX metaphor was a good one, as definitely crystalizes the "many specific parts" approach. I suppose I just wasn't in that mindset due to the presence of aliases, AppleScript, and ".app".
Saying cron is based on launchd is a bit of a stretch. The cron process itself is launched by launchd (since we don't have an "init" anymore), but from then on all cron tasks are handled by cron itself and launchd has nothing to do with them. That's just due to launchd replacing init.
cron was deprecated in 10.4 (four and a half years ago), whether explicitly or implicitly. This "unique" way of scheduling certainly took me forever to find - the only reason I did was when I got error messages as a result of it. Since you require 10.4 or later for SuperDuper, you always have launchd available. From an end-user perspective I can see exactly where launchd is configured (Library/Launch(Agents|Daemons)), monitor, start, and stop processes as needed (launchctl), and make changes easily with a multitude of tools (Lingon, etc). For cron there's no reason to suspect it's running at all since Mac OS X doesn't use it, there are no configuration files on disk that I've been able to find, and the default editor (vi - which I finally managed to change to nano) is about as arcane and unfriendly as it gets.
Unless there's a specific launchd bug on 10.4.11 that I don't know of, I don't see it buying you anything. The only change I see would be writing a plist to /Library/LaunchAgents/ instead of a line to cron.
As for AppleScript vs Objective-C, I can completely empathize. In their attempt to make AppleScript "readable", they certainly made the syntax unpredictable. One of those things that sounds good in theory, but doesn't actually work all that well. However, AppleScript is the only option for most people to automate Mac OS X applications, so it is what it is. Any chance of that "error" keyword getting a tweak?