Backups Multi Bay drive unit

I have a Sabrent multi bay enclosure which rocks. I like to keep multiple backups, time machine, clone etc. I always thought I should have at least one back up in drive in a separate enclosure in case of failure. The multi bay one could die and maybe all my disks with it. (not sure about that but I assume.) I do swap one drive out offsite each week. Is it unnecessary to use different enclosures or am I ok with keeping everything in the multi bay? If the controller on the unit dies, would the drives themselves be ok to pop in a new unit and go?