Anand wrote "I spent a good amount of time trying to work around this issue, even manually setting TCP window size in OS X, but came up empty handed. I’m not overly familiar with the networking stack in OS X so it’s very possible that I missed something, but I’m confident in saying that there’s an issue here."

I wonder if he tried net.inet.tcp.win_scale_factor=8 and kern.ipc.maxsockbuf=16777216 as recommended by http://fasterdata.es.net/host-tuning/osx/ and other sites?