All and all testing was pretty dull and considering what kind of devices these are, this is a good thing!
Both the BPU-340 and the BPN-DE series hard drive enclosures have a solid build and functioned as expected. They are simple and elegant and do exactly what they are designed to do. The BPN-DE series does have a clear advantage over its little brother as it supports SATA 3 and carries a trayless design. The aesthetics are nicer and the construction contains much more metal which is simply going to hold up longer over time.
Even though it is slightly more expensive, I would recommend just getting the BPN-DE series as there just seems to be little reason to get the BPU-340 when comparing the two.
iStarUSA seems to really be backing this model, too, as there are several different color options out there and other enclosures for single drives. This enclosure is also worthy of a business environment with its solid construction and support for higher-end SAS hard disk drives. Though the BPU-340 is nice and there are not a whole lot of negative things to say about it, the BPN-DE is far superior in just about every way and therefore earns our Gold Seal of Approval!