I think it much depends on the upload speed of the original seeder, as to how fast torrents will download. The advantage is that although you are uploading simultaneously, you can usually limit your upload speed, but with some clients (I am not familiar with emule), this also adversely affects your download speed. The emphasis with emule and the like is 'sharing', and you only get back what you are prepared to put in.
The problem with Limewire and Kazaa, as you will no doubt be well aware, Dave, is spyware, particularly in abundance on Kazaa (which also seems to contain the most viruses), unless you have either Kazaa Lite, or *cough* pay for Limewire Pro. Another disadvantage is that you are potentially sharing back more than the one file you are downloading, and caution should be used when setting up these programs, so as not to allow everyone and his dog access to all the files on your PC!
I think there's a balance between the two, especially if you have a fast connection. I tend to leave torrents downloading / uploading overnight, but these are usually fairly large files. With Azureus, or Bit Comet, I can download roughly 700Mb in around 4-5 hours, depending how many seeds there are. I have also found that torrent clients generally don't seem to contain spyware, unlike many of the 'free' versions of the P2P sharing clients, such as Kazaa / Limewire, etc. For a free (and spyware free) P2P sharing client, which also doubles up as a torrent client, I would suggest trying Shareaza, which can easily be found on any search engine.