Chowder - More than once, I have said "I'll never need more than that". I have always been wrong. I recall you are retired, I am still an active consultant. I am sure you know, but, you Neff three drives for RAID 5. RAID 5 will not loose any data on a one five failure. You need 4 drives for RAID 10. RAID 10 will not loose any data if Terri drives fail. So, why not throw in an extra drive and why not tetras, as long I am dreaming about things I cannot afford.
BTW I hear you on the XT. My first system was a TRS-80 with a homebuilt 4 floppy enclosure. 360 K 5.25" drives.