Ardsar,
I've also noticed that my SNR is around 1dB lower on this device than the HG612. I'll need to confirm this later by reconnecting the HG612 but if I remember right, I was sitting at approx 7.5dB with that and now I'm around 6.3dB.
I think there may be a slight issue with sync rates as it appears I've lost a chunk from the down and up stream attainable.
D6400:
Max: Upstream rate = 26040 Kbps, Downstream rate = 80441 Kbps
Bearer: 0, Upstream rate = 20000 Kbps, Downstream rate = 74000 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
D7000:
Max: Upstream rate = 16707 Kbps, Downstream rate = 75277 Kbps
Bearer: 0, Upstream rate = 16730 Kbps, Downstream rate = 74000 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Other users on Whirlpool forums have noticed the same. I'm not too worried about it as I'm still syncing well above what my Asus device could and it is far more stable.