Are you serious? The goal of RAID is to eliminate downtime; a drive fails and you pop in a new one. All without ever having to reboot or even stop working.

With Time Machine, you still have to manually rebuild your system after your drive fails. This is not what Time Machine is for; it's for, "oops, I shouldn't have deleted that file". (Which, incidentally, RAID is not for.)

RAID + SSD = no TRIM (cept for recent Intel drives). That's a problem. It's easier (and much cheaper) to just have a bootable backup that's updated nightly.

Even a RAID1 failure requires you to have a replacement (ie, trip to Fry's). A bootable backup, however slow, is just there.

Pretty sure this is not the case for Linux. LVM supports discard, so md probably does as well.

Also, you don't immediately need a replacement drive: RAID1 boots fine with only one device. Assuming your company policy is to have RAID1'd SSDs for all developers, you're probably going to have extras on the shelf anyway.

Time machine is for accidental data loss. RAID is for disk failures.

Exactly.

A nightly differential bootable system image backup a la SuperDuper, Macrium Reflect, Acronis or the like + cheap external 3TB drive = zero downtime... if the SSD fails, boot from external, and schlep it while the SSD is repaired/replaced.

Time Machine is bonus for lost/overwritten local files. Source Control guards the jewels (you don't fear committing untested code to local branch, do you?)