I believe the Stripe size now is 9MB on Adaptive Flash and 10MB on All-Flash. This is due to the following:
Triple Parity RAID -
On the latest Adaptive Flash Systems, the disk layout is 18+3 for HDD. 512k/disk on 18 disks = 9MB
On the All-Flash Systems, the disk layout is effectively 20+3+1. 512k/disk on 20 disks = 10MB
Make sense? Let me know if I can answer anything more.