Agreed.
Also, larger disk drives tend to become less reliable in my experience.
I have a server where daily roll back backups is made to a 1.5TB drive every 24 hours. Given that I only do a rollback of Inetpub on that drive I get about 170 to 200 days worth of dailies out of it.
I would love to slot in a 3TB drive or larger, but reliability is such that I would rather swop out the drive for a new one twice a year and put the full drive in a "storage" server at the office than risk losing a year worth of roll backs due to a drive failure.
(Before anyone flags my backup method, we do have other backups on three other servers, but since these have 1.5TB drives for backup at the largest and they serve as backup/failover nodes for eight servers total every server has a rollback backup drive in it. We are a smallish setup that cannot afford a SAN setup, so we make do with what we have. That means that per server we can keep about 30odd days worth of failover backups on these servers. Again larger drives would be great.)
Anything larger than 1TB also become problematic in a RAID setup, where I found the Seagate NS drives to be almost bulletproof - up to 1TB. I would not trust anything larger than that in a RAID array just yet.