That should usually be plenty as the folder is usually empty or close to empty. I don’t monitor this folder constantly though and I’m guessing there may be peaks. Would be best to have a fallback as a full ramdisk would result in every upload failing. I guess that’s not fatal though.
Also, I have definitely not tested this suggestion so try at your own risk. But I think you have more then enough nodes to try this with one or two. Do report back on your experience. I’m kind of curious whether this would relieve some of the stress on the HDD. If so we might want to request a feature to make the temp path a setting (just like the db path). The temp path is kind of an ideal fit for a ramdisk as any interruption that would cause the RAM disk to lose data would also fail the ongoing transfers and make the temp files obsolete and it should only impact ongoing uploads at worst.