Re: 4Tb drives, I do the dollars-per-mb calculation before buying hard drives. The most recent time I included the enclosure cost and found that it was actually cheaper to go huge. Granted the enclosure was a Synology, but buying 16TB drives is the closest I’ve been so ‘solving’ storage in a long time. Formatting them and adding them to the array was brutal, and they are noisy, but it has been worth it.