Think I've sussed it?????
 

Hi everyone. Read with interest all posts, and think I have sussed out the up/l d/l thing. Just one query regarding fluctuating d/l speeds. Would it be prudent to assume that if the speed varies, this could be because the host has more up/l traffic thus when one up/l finishes it can free up more bandwidth for me and others?

That's about it, many things happen, just look in the monitor window how uploads speeds will vary for each host. The speed changes are very dynamic and multi factors.