Which would, in turn, leave the OP still dissatisfied because his point was that he didn't want to install another downloader.

Yeah, that was odd, considering he used e.g. Blizzard's proprietary p2p-client as a good example of how to do it. Blizzard does not use common Bittorrent clients for their p2p transfers.

Naturally in GOG's case it would be part of their current downloader client, with e.g. a "use p2p to speed up downloads?"-checkbox.

I think most people just associate Bittorrent with piracy and are reluctant to be associated with it. The GOG downloader has never worked for me at all and most of the time i have to download with my browser which is ok for small games under 500mb, but larger games times out and i lose all the data, my internet is slow (56k/sec DSL). The downloader quality and size of the game is my main consideration when i buy a game, so my policy is to not buy games over 500mb on GOG, sorry, but the downloader doesnt work for me. Im sure im not the only one, its a very serious problem and GOG needs to improve it.

There's that, but I think the main reason that I'd like to see bittorrent is that it better handles broken filles than the downloader does. You can just download one chunk. AFAIK the downloader checks when downloading and that's it. If the resulting file is bad you have to redownload the entire file. Which is possibly 2gb ultimately. I do kind of like bittorrent as an option, but I don't think it makes much sense for GOG. For Blizzard and Runic it does make sense as it's pretty much guarantees that when they roll out a new patch that there will be enough bandwidth in the right places for everybody to get their download promptly.

Here, the only time that's a problem is when they release a major new game, like say if LA were to be signed or they managed to get rights to System Shock squared away.

Other than that, bittorrent is vastly superior to the downloader in terms of resilience. If a file later on gets corrupted the downloader would download it again from scratch as far as I can tell. And doesn't seem to address the problem of files being corrupted later on at all.