DE110 - 3.5"
A bracket must be lifted before the drive in the 3.5" DE110 model can be removed. However, a key has to be used here too, which adds more safety against removing the drive accidentally. Any 3.5" hard drive works in the DE110, which these days translates into anything up to 400 GB. Dantz Retrospekt Express is included as the backup software.
In contrast to the DE50, the DE110 is probably better suited for operating medium-sized RAID arrays, since 2.5" hard drives play basically no role in the server area. The exception is Seagate's Savvio; it, however, is intended for intensive continuous duty and not for comparatively undemanding backup purposes. In general, though, professional drives with SCSI interface are a step up from devices that could be interesting for data backups.
The DE110 is available in several models, with UltraSCSI, UltraATA, Serial ATA or with USB interface, as tested here.
Both StorCase devices make sense particularly if you deploy several of them in a large case to create an easy-to-maintain RAID array. However, in this situation, preference should be given to a model with ATA interface. Several plug-in units and hard drives can also be acquired for simple backup purposes and regular archiving.