Keep in mind things change... years down the road you will have to switch to another 'cloud' service. The smaller you make your backup the easier it's going to be.

iDrive lets you send them a drive, but you'll be paying $100 per year to save 5TB.

The 'Unlimited' places do the throttling to keep costs low. IMHO, just plug the drive in and let it take weeks to backup if you can't clean up the drive.