In this thread http://forums.adobe.com/message/4332410#4332410 Eric Chan states that the Profile Editor does not work with PV2012 profiles but that he is working on an updated version of Profile Editor, but that it is not yet ready.
Correct, DNG Profile Editor doesn't support PV 2012 rendering. (This is actually probably a good thing, since the DNG PE is about defining the baseline color response, rather than judging the combined effect of the color profile + ACR adjustments.)
I use DPE also for custom adjustments to individual photos, and have a way of "hiding" the multitude of per-photo profiles so they don't pollute the global profile names list. That's when viewing the image with adjustments is really helpful.
I look forward to the new PV2012-capable DPE version.