Internal vs external storage

Hi !
I have been thinking about how to store my pictures in the future. For the moment, I have a big desktop (windows), with a bunch of internal 3.5'' SATA hard-disks, plus 2 SSDs (one for the system, one for scratch). I have several lines of backup, first one: a data HDD is backup up internally (with sync toy) to another (almost) identical drive.
Then, every time I ingest new pictures, another copy of the data drive is made to an external disk, stored at work.

I think this is a pretty safe and sound approach.

Now, I have started to wonder, if I would gain something by replacing or migrating some (or all) of my drives into an external (RAID) enclosure. It seems like a trend these days, that the big tower desktops give way to a combo of a smaller desktop (or laptop) + an enclosure.

I do like the idea of having a laptop instead of desktop (it would allow to have all my images with me while on the read, in the form of smart previews), and reduces the number of machines to own (everything in the laptop). But would I be giving away performance ? Any other aspects to consider ?

Do you still trust the "big desktop" approach, or do you now favor a split scheme ?

Thanks for your ideas !

I have a desktop PC, and I use external drives. None of them last forever.

Big monitor. small CPU. My choice.