I’m having involuntary eye twitches thinking about this…
First and foremost, you didn’t say whether you’ve got a consistent, regular backup system. In a RAID0 configuration, any one drive failure in the set will cause all of your data to be lost, right now. If you’ve ever had a spinner fail, you know that RAID0 is only for disposable, don’t-care-if-it-dies-unexpectedly storage.
Second, volume format can play a significant role. For spinning disks on a Mac, I’d stick with HFS+, as APFS is optimized for SSDs and can bog down a mechanical disk. ExFAT and FAT32 don’t have robust journaling and can cause problems with databases and certain types of file metadata, so I only use those when I’ve got to share a drive with a Windows box.
In the Energy Saver pane of system prefs, there’s a toggle for spinning down when possible. If this is turned off, and you’ve done the terminal command, and it’s still spinning down, zapping PRAM and/or resetting the SMC could resolve it on an Intel Mac. No such options on the AS models.
I’ve had a several different RAIDs, and the most trouble-free experience was with an Areca 8-bay Thunderbolt 2 box loaded with 2TB spinners in a RAID6 config. Glad I had the 2-disk failsafe, because I had a drive fail and during the rebuild a second drive failed. Didn’t lose anything except a little time.
Right now, I’m using an OWC Thunderbay 8 loaded with SSDs, configured with SoftRAID. It hasn’t been quite so reliable, but it is always blazingly fast. I run nightly LTO backups, and do a weekly clone to another old box so I can sleep at night.
EDIT: As for the BMD Multidock, Disk Utility has the ability to take multiple attached disks and create a RAID, though it is fairly limited in its options.