Hi and welcome to the forum and - hopefully - to the ever growing family of DEVONthink (DT) users. A little while back a user here asked what the advantage is to using DT; whilst that thread might contain some responses which are not relevant to you, you’ll certainly get an overview of some of the advantages to using DT there.
Whenever you consider moving your data into a new system, it’s worth considering how you you would get it back out again if you ever needed to. DT stores your files unchanged in their original format; they are actually accessible from Finder from within the database files (useful if all else failed; and for anybody passing: no changes should be made to the database structure from within Finder!). It also includes a simple export function which will export your files to Finder using a folder structure equivalent to your database structure. That’s important - imagine using an app for 10 years, the developer goes bust, mad or megalomanic, and you can’t get your data out.
DEVONthink ticks more boxes than you can probably imagine; it is a stunningly powerful tool supported intensely by the developers and the amazingly helpful people on this forum (@SlickSlack called it a unicorn - I agree, this place is unique).
You will need some time to get used to using DT; whilst powerful it is also flexible - numerous paths can be taken to achieve the same goal. You will probably need to play to see what suits you best. Again, I can do no better than quote @SlickSlack, who said DT grows on you - I started with simple data storage and ended up with complex automation. Great fun!
Please allow me to point out that DEVONthink does not automatically back up your data (it does keep some internal backups of the database structure). Whilst it does offer various options for syncing data, they are explicitly advertised as not being a backup. The more you use DEVONthink (or any other type of database), the more loss of data would hurt. If you haven’t already, I recommend you take the opportunity to see whether your backup strategy is suited to the importance of your data. There are a number of threads on the topic here in the forum; here’s one of them.
And finally, it’s worth taking a look at the different editions of DEVONthink; this page provides an overview of what the Pro and Server editions offer on top of the functions offered by the Standard edition. All licences include 2 seats, so the app can be installed on two Macs. I personally feel DEVONthink only comes into its own when you have the Pro edition; OCR, e-mail archiving, concordance and custom metadata are invaluable to me.