Actually, Bittorrent is something I've considered for a long time. The problem is this:
1. The torrent cannot be changed easily without making a mess [this is the biggest problem, with no solution].
2. There is no stable "source". I suppose this can be sort of mitigated by using web-seeding, but this is not a function all BT clients have.
At first, I considered using BT as the primary distribution route, but these problems got in the way majorly.
Currently I'm still planning to use BT, but for the distribution of image backups (I'm still thinking of ways to make the bulk of IMSLP minus sensitive information accessible via dumps). In this respect the issues with BT are slightly less problematic. And no I've not forgotten about this
: I've been planning to make IMSLP's databases accessible (as dumps) piecemeal. The problem is that IMSLP has a non-standard database setup which is different from normal Mediawiki, so a straightforward dump may not be a good idea, while XML dumps would miss some of the important parts of IMSLP (the index, etc). I may in the end settle on a mixed XML/MySQL dump. The files will come later in BT torrents (and is much more of a headache, especially automating the process).
With regards to sharing things on DC++, that is fine with me; though in the end everything needs to be on IMSLP (to prevent scores from disappearing, etc).
Maybe you can set up some page describing the process, Funper.