gwlim, you're a human above all others.
Took me a moment to figure out what the hell SFE was, but when I did, my speedtest.net results improved.
My internet connection speed is 2.5Gb/s down, 1.6Gb/s up, so it takes three machines at gigabit speeds to saturate the line for download, and two to saturate the upload.
Before SFE: 220Mb/s download, 186Mb/s upload. Enabling SFE: 816Mb/s download, 262Mb/s upload.
Ping times for tests were 0-1ms, so that's fine. I tried several different speedtest servers, and couldn't really get results that were faster on the upload. I plugged my laptop directly into my modem, and still couldn't get more than about 260Mb/s, so screw it. I'm a happy boy and my remaining problems are upstream of this router now. Will check again later tonight when the speedtest servers are a little quieter, maybe.
So yeah, OpenWRT and the Netgear WNDR3700 CAN push through over 800Mb/s and are not quite obsolete yet. The other people in this thread might want to revisit their problems.
Thanks a bunch!