I know it's bad form to resurrect an old thread but I figured future searchers might benefit, so why not.

As of this date (7/4/2017) Saris, a.k.a. Cycle Ops, a.k.a. PowerTap, has PowerAgent 7.9.14 available from their Web site. I got a "pre-owned" CycleOps wheel with a g3 hub, and set about trying to update the firmware, since the wheel had been sitting around for a few years. Long story short, PowerAgent 7.9.14 is basically worthless on both Mac OS X 10.12.5 (Sierra) and on Windows 10.

So I searched a bit, and located this directory on the Saris Web site, which contains PowerAgent 7.9.20, dated 6/27/2017, in both Mac and Windows versions. A lot of other stuff is there, as well.

I'm still unable to update the firmware on my hub, but it pairs with my Edge 510, so whatever. But maybe I'll call them to see if I can learn anything.