When you select AHCI,, you are also selecting RAID. AHCI is a RAID function. or vice versa.
Uses of RAID,,, if not striping several drives for speed (which you can get using 3+ drives), you can also mirror for redundancy, and yes, It saved us about 300M of wife's family pictures, our MP3 library, among a ton of other things, which would all be gone now. So, yes, there are practical home uses for RAID.
I recommend at least, 1 drive for the OS and 2 set up as a RAID mirror for data, and then also an external drive for running weekly backups.
But, it all depends on how much your data means to you.
There are 2 kinds of computer users in the world.....
Those who have lost data and those who will lose data.
The choice is yours.
Edit*** don't know why I wrote the viceversa,, cause that is actually wrong. RAID is RAID and AHCI is RAID, but RAID is not AHCI.