Not sure what you're doing with your things, the WDR3600 and/or WDR4300 works great (at least using atk9k driver) but like with any wireless router you need to do a wireless survey to figure out what channels you should use and channel bandwidth for best performance. Also, update wireless drivers on your devices as it can affect them greatly on how they perform.
I always stuck to auto, how do I do a survey?
And yes, I love TP Link, but I couldn't wait for it to be shipped lol.
I went to Best Buy, Wal Mart and Frys tonight, none of them had a TP Link dual band router, kind of surprised too by that. So I ended going with the Netgear 6220.
That 3600 is only like $50 on frys.com , if they had that, I would of picked it up for sure.