I got my SP3 today and the first thing I did when I got home was hit the Speedtest website. I'm happy to say that I got 50MB down--I'm a happy camper!
I have 50mb service from my cable company, and my router is about 15 feet away with direct line of sight. When I run speed tests on my iPad, I typically get around 24mb down. Although I rarely have any problems streaming, it would still be nice to maximize the connection.
If it's cable, they always mumble about "up to" speeds.