The HPNA performance is going to depend on the number and quality of phone line splices in your house.
At my house, I have my phone lines spliced in a dozen different ways, for multiple modems, fax machines, extra phone extensions, answering machines, etc. And they're not nice clean in-wall splices, they're done with external plug-in splitters and half-assed wiring schemes. In some cases, I'm deliberately trading the line1 pair for the line2 pair and back again. I'm doing more with my phone lines than most other sane people do in their houses.
So when I tried the receiver with HPNA, I discovered that it would only work if I unplugged a couple of the more flaky connections (specifically, the computer modems), and would tend to work best if the products in question were connected directly to the wall jacks with short cables.
If I tried daisy-chaining the receiver through another device (such as through an external splitter to one of the modem connections), then the HPNA connection was flaky.
So I resorted to running ethernet and haven't looked back. In retrospect, I could have achieved satisfactory results with HPNA by simplifying and cleaning up all of my external wiring splices. Another possible factor is that I was using some pretty long cable runs with flat phone wire, which might have been improved if I'd replaced the flat wire with twisted-pair wire.
So HPNA is easily do-able as long as you haven't rube-goldberg'ed your phone system.