For my observation (in different areas, different languages), it not depends on RAID-type, not depends on volume sizes, HDD sizes. It's a lot of weepeng around the world.
For R5 - chance to halt is higher, because CPU utilisation higher.
On JBOD - chance exists (less, then R5, but ALWAYS exists).
If ONLY ONE client connected to NAS at one period of time - all right, all can work week by week with R5 or without R5.
> I've been using one DNS-343 for well over a year fully loaded with 1.5 TB drives
Firmware with support drives >1T released few month ago.