I had my 20mb upgrade to 50mb yesterday and I'm getting fluctuations too, although I believe it may be due to network congestion what with it being the weekend. In usenet right now it's mostly at the full 6200 k/s however it drops around 5000 then sometimes to as low as 1000 (5mb) then slowly rises again.
This morning about 12.30 it was constant full speed this is why I assume my problem is just network congestion, perhaps that's partly responsible for yours. I too had a rock solid 20mb most of the time.
Here are my power levels, I assume these are okay for those in the know?
