Since you asked for a brain dump...😁
Cloud-based storage is a tough option right now due to cost and control...iCloud would be out as the storage capacity is too small for a high level user.
An external drive is still prefered way for me...but consider some creative ways to accomplish this. I use three external drives right now...they are all 2 TB drives from OWC, http://www.macsales.com, their Mercury Pro Elite quad interface drives. So they can attach using Firewire 800/400, USB, or eSATA...gives a range of speed options and connection options depending on the base system.
I have ordered another of those drives, a 3 TB drive, that will be dedicated to iPhoto files, scans of the many thousands of slides and negatives I have and want to archive digitally. That drive will only be attached when I want to work with the images.
That comes to a creative approach...if you do not need to backup daily, you can dedicate a drive to only backups, attach periodically, and either backup or clone the internal storage, and backup other external storage. Eject the drive when done and store it some place safe. That way you have the best of both worlds, regular backup and safe store.
You can keep an external drive attached for normal use such as TimeMachine backups that keeps your current material available at all times.
As to longevity, my OWC drives have been attached for one and half to two and a half years, different drives on different machines. They have never given a hint of a problem, and are used daily. The MacBook Pro and iMac are used for hours every day, two of the drives do TimeMachine backup, as well as various versions of Mac OS X so are repeadtedly being accessed. Drive longevity is highly dependent on the quality of the hard drive.
My personal opinion, and not trying to sound like advertising, is to always use OWC when I can. They are Mac specialists, only do Macs, no PC work. Everything they sell has been tested for use with Macs, their drives come pre-formatted for Mac OS X. If you are not familiar with them take a look at their website and see the range of things they offer.
Guess this is crossing over into the rambling category now so I best stop and see if you have more questions.
Ralph