I've been lurking and keeping an eye on this thread since I purchased my Surface Pro 3 last month. Like everybody else, I was affected by multiple problems: link speed maxing out at 72 Mbps on the 2.4 GHz band, awful throughput, and limited connectivity
after resuming from connected standby.
The latest September driver update has resolved most of my issues. However, a big one remains: when waking up from connected standby, Wi-Fi quality degrades and remains that way until the Marvell AVASTAR wireless adapter is reset (i.e. disabled and reenabled).
This is not obvious if one is merely browsing the Web, but attempting to stream, say, recorded HDTV on Windows Media Center results in an infuriating buffering mess until either the Wi-Fi adapter or the Surface is restarted.
While in this degraded state, the driver reports a normal link speed, but actual throughput drops to a fraction of what it should be, and the connection is riddled with random stuttering and latency spikes, with pings to LAN hosts jumping from the normal
1-2 ms to anywhere from 200 to 2,000 ms.
Manually disabling and reenabling the Wi-Fi adapter every time I woke up my Surface to stream video got old really quickly, so I figured out a way to automate this that I've described in my blog:
http://blog.blazis.com/surface-pro-3-connected-standby-wifi-degradation-workaround/
While not ideal, this will tide me over nicely until Microsoft (hopefully) releases the ultimate fix.