I've often said that the new disks, and their controllers, are impressive.
I once reduced my size from 42 arms down to 7 and got much better response
time. I ran a BPCS month end as a test. The old machine, with no
additional work load. With the network cable disconnected. Was a dog
compared to the new machine running a month end. With it also serving
multiple Domino servers, etc. And multiple users banging on the machine.
Since then some of the newer larger drives are only 10k vs 15k.
IDK if they plan on making that up with better controllers, or, if they're
more intended for lesser used data.
Some people are recommending a mix of SSD's along with the big honking
drives. Let the system balance the faster data to the SSD's