I am seeing a similar thing here.
The FC2 machine is connected to a T1 network, yet I can only upload with about 20KB/s. Both scp and ftp behave the same. The connection also stalls quite frequently.
Interestingly, if I open several connections simultaneously, they do not affect each other.
For example, I was able to split a big file that I needed to send into 20 pieces, and to send them all together achieving an average upload rate of around 400KB/s. This also shows that there is no problem with the connection itself.
I tried with different kernels from 2.6.6 to 2.6.8 and they all behave the same way.
Any help would be appreciated.