This may not help with a crontab alternative, but a few of the traps I've been caught on in cron in the past are:

* Environment is not set - so if you need a path or environment variables, you need to set them yourself. This is the biggest. If you want to remove this as a suspect, explicitly declare all environment variables and call everything by absolute path.

* Right times in the right columns - one "day of month" in a "day of week" or other column switch can lead to results you were not expecting.

* Other cron jobs interfering - had one cron job that was flaky, found out it was because a differnet cron job was modifying the data file at a certain point, and if the first hadn't completed odd things happened.

Hope this helps,
=Blue