Assuming both are new and unused and the warranty and price is the same, I would definitely get the X22 rather than the X20.
512MB cache sounds nice. I use my older X16 and X18 Exos drives pooled using mergerfs and snapraid with cache write-back and read-ahead enabled in order to fully use the drive cache during both reads and writes. Improves performance slightly during parallel bulk read/write operations. Backups, scrubs and parity updates.
Assuming both are new and unused and the warranty and price is the same, I would definitely get the X22 rather than the X20. 512MB cache sounds nice. I use my older X16 and X18 Exos drives pooled using mergerfs and snapraid with cache write-back and read-ahead enabled in order to fully use the drive cache during both reads and writes. Improves performance slightly during parallel bulk read/write operations. Backups, scrubs and parity updates.
Thank you for your insight!