I decided to go with this. I like that it's purpose-built, and while Western Digital isn't exactly a trusted name in networking, I've used their products for things like this before. Sometime around 2010 I used their powerline products and was very impressed with them. Hopefully this will be a similar case.

Thanks for the help, folks. I'll let you know if the third time's a charm, or if I end up sending yet another product back (the reviews don't give me a ton of confidence). I wonder how many things Amazon will take back before they start complaining...