I use Speed Download 2 also. It's ok, though my experience is that resumed downloads are usually corrupted. Another problem I have is that stalled downloads rarely resume by itself (I've been assured that this will be fixed in the next release).
Happens to me too, sometimes, but not often enough to be a real bother. Maybe just once or twice, so far. I like the fact that I can just copy any download link from a webpage and add it to the queue, and SD just goes to work on it. The one nuisance I sometimes come across is when I don't throttle the bandwidth. SD tends to tyranically usurp the entire download stream, even from non-SD downloads already in progress or simple browser requests to create a webpage, and it strangles everything until they choke to a dead stop and it just chugs along selfishly, full-bore, until it's sated and finished. Good for your download, since it comes down the tube as fast as possible, but it disables you from doing anything else that requires bandwidth. [Edited on 1-4-2005 by Adel]
Just curious. What's the main use for a download manager? I still am able to resume downloads using the default download manager that comes with Safari. Does it really accelerate downloads? What other nifty features in a download can you NOT live without?