Can the DS425+ use 2 Drive bays as Raid1 and 2 As If They Were External Drives?

My QNAP 251+ died, but the 2 WD Reds are fine, so I'm looking at the 2025 models since they seem to be compatible with the Reds. I was using the 2 4tb drives in a Raid 1 set up with about 2.2 tb used and my needs are growing much slower than they used to. This is a low demand home set up. Aside from storage, the other primary use is Plex (maybe Jellyfin going forward).

I could easily get by with the 225+ and use bigger disks if/when I need the space. The one reason to go with the 425+ aside from being easier to grow space would be if I could use the extra 2 bays as hot swap drives (or even cold swap) most frequently for making backups to standard ext3/4 or NTFS drives. I assume that would be much faster than the USB dock I've used in the past.

Would that work? Any other reasons to I should go with the 425+?