Is Bluetooth on or off?
It is the Power Management on the updated WiFi Driver.... killing Bluetooth will negate the Pen and also cause errors in Connected Standby (potentially preventing it from working).
If that's the case, an online speed-test should give you a better idea. My Verizon FiOS service is rated at 50 Mbps up/25 Mbps down. On my SP2, I test around 25/25 with Bluetooth off, with it on I test around 10/20. On my 3 year old ASUS laptop, speed test results are consistently 50/25, regardless of Bluetooth setting....does the SPro3 just show the reduced WiFi speed at idle and increase speed as needed under load?