As I know, AutoFlight manages just alarms, keylock and can automatize some operations like switch for flight mode on/off, call forwarding, profiles, reset etc.
DontForget is mainly designed to comfortable remind you about missed events (like SMS or calls) and in addition can also do similar things (partialy) like reboot your device in given date/time or switch profiles or flight mode on/off.
More you can read here:
http://magazin.softimage.cz/dontforget/app-description/