Uploading is done at 512k
bits per second, which in real terms equates to (512/8 = 64) 64k
bytes per second. Which to me means in uTorrent which measures in Bytes, not bits, says you're basically maxing the upload out each time.
Doing the same sums for downloading, would mean that your 10m
bits per second connection tops out at (10240/8 = 1280) 1280k
bytes per second, which also says to me you have seen the max your line can do when you hit 1000kbps+ when downloading.
It's all in the bits and bytes, which i admit are confusing
Remember, 8 bits = 1 Byte.
Hope this helps you