You asked. I agree. I think your backup plan is excellent. I don't like backing up to computers, but again, 100 people, 100 strategies. I think having three weeks worth of data is incredible and would put you in the top 2% to 3% or higher of those backing up here.
Jungle Disk is great, mainly for its de-duplication that most online backups don't use.
I think, since you asked, the only thing I would change would be that you make your "last resort" weekly instead of monthly.
I agree with your strategy given a non-server computer to just start over. It is likely better and you can upgrade your computer. But, again, I am not just talking a computer meltdown or a hard drive crash. What about the occasional virus or some other calamity. You have you applications and your backups but why not try the restore in 45 minutes and see what you have left.
How often have you had to go to your backups to retrieve a lost file?
How often have you had a flood or a fire?
