LadyF -- I agree with your post #3 for the most part. I only disagree slightly about data partition [data folders & files] backups. I've been doing full images [with Macrium Reflect and a tiny bit with Image for Windows] of my data partition for some time now -- and have not encountered any problems. Now, I totally agree with you if, daily or even weekly, many many data folders and files are being added, deleted, modified, and so on. Because the vast majority of my data folders and files do not change, full imaging for now
In your case, imaging is fine. Actually, it is fine even if one has to image frequently. The only downside is the amount of time to make an image due to the time to make a full image (I do not recommend incremental or differential imaging) and the amount of drive space required to store multiple images, which can be unacceptable if, unlike you, someone has a lot of data in flux.
In my case, I always make an image before making any kind of a change to my desk top computer, such as updating a program or the OS, adding a program, etc. While one often can uninstall a bad program or OS update, it's usually more complicated and time consuming and often less reliable than simply restoring from an image. Also, some changes can brick a computer so having a recent image to restore from is a huge time (and bacon) saver.
I'm frequently adding, deleting and updating data. I also have a lot of of it: around 3.5TB of it. My machine also serves as an HTPC (Home Theater PC). It is my stereo system. Except for a few I bought recently, I have ripped all of my CDs to the computer and play them from the computer—it's playing music through a 2.1 system right now. The computer also records OTA (Over The Air) TV shows and movies, up to four channels at a time. Most of those shows get deleted once I have watched them, so that is one heck of a lot of data both coming and going.
I have three data drives in my computer right now (my next rig will start with four) and making a full image of every one would take hours, if not days, and would require multiple times more drives to store multiple images than what I'm using now (12 HDDs; I'm a firm believer in planned local and geographical redundancy) whereas making backups with a folder/file syncing program can take as little as a handful of minutes, depending how much data has been added or changed since the previous backup.
Now, in the case of my notebooks, which get used only for travel and if my desktop rig is down, I only image the OS partitions. I don't bother with the data simply because it comes directly from one of my desktop drives which is already backed up. If I loose the small amount of data I keep on a notebook (mostly just music and e-books) while on the road, I can always recover what I need from my Carbonite cloud backup as long as I have a reasonably secure internet connection (I also carry a cloned drive I can directly access for data in addition to an image storage drive in my notebook bag).