When I previewed these results with Belkin, they asked if they could send a Gigle Field Engineer to my home to make some measurements and to see if they could improve the performance that I experienced. The Engineer confirmed my results and then tried some changes that did result in improved performance.
But even with the changes, it still looks to me that Gigle has some work to do in order to produce better-than-HomePlug AV performance for outlets around a moderately-sized home and especially through AFCI circuit breakers.
Also on Gigle's To-Do list is getting its mesh xtendnet technology to actually boost throughput in low-throughput connections via the addition of an adapter placed somewhere in between. I was not able to see an throughput improvement from plugging in an additional adapter while running tests to my lower-throughput Locations E and F.
My experiments were complicated by the fact that Belkin doesn't ship a utility with the kit that could tell me how the adapters are configuring themselves. Of course, such a tool exists, and was used by the Gigle Engineer to confirm that the third adapter he plugged into various outlets in my home was, in fact, configuring itself in a mesh connection. But as I monitored an IxChariot data stream while he plugged and unplugged, I never once saw a boost in throughput, even when the Gigle utility was showing a mesh connection for the adapter.
Despite its current problems, I think Gigle's technology holds promise for improving the speeds available to powerline networkers. And the fact that the Gigle engineer was able to make software-only changes to enable the adapters to go from no connection to producing low, but usable throughput in my difficult test locations and behind AFCI breakers is encouraging.
But unless you want to participate in a science experiment, I suggest holding off for a few firmware revisions before trying out Belkin's Gigabit PowerLine HD kit. And don't count on the "mesh" capability for now. I think that feature is going to take a lot more work to make it work reliably. At least from what I saw in my comparative testing, between the Belkin and NETGEAR XAVB1004 kits, the NETGEAR wins.