Check Point 2 (cont)

http://www.bittorrent.org/bittorrentecon.pdf
http://www.pam2004.org/papers/148.pdf
http://portal.acm.org/citation.cfm?id=1015508
http://research.microsoft.com/%7Epadmanab/papers/msr-tr-2005-03.pdf
http://www.zhenxiao.com/papers/jsac2007_bt.pdf

Basically, the salient points are
* BitTorrent doesn't allow for sending individualized files to clients, because it copies data from client to client. This is a non-issue because iTunes applies DRM after downloading the file anyway.
* BitTorrent is fastest initially (when lots of people are uploading so that the protocol will allow them to download) and tapers off later as less people connect to the torrent. This will not be a problem with iTunes, because (a) uploading will be legal (assuming Apple does the appropriate licensing) so people will not 'turn off' their uploads, and (b) iTunes can force people to upload all media on their systems.
* BitTorrent is slower for unpopular files. Apple can deal with this by having its own, high-bandwidth seeds for all files. In the case where only a few clients with little to none of the data are connected to a torrent and there is one seed, the service becomes very much like a traditional download.

As far as experimentation, I plan on comparing the download time for a reasonably popular, but not recently released movie (namely, the first Pirates of the Caribbean movie) via both iTunes and the official BitTorrent client on the same system and comparing the total download time and system characteristics (ie, slowdown) while downloading. I expect the time to be somewhat slower for the BitTorrent because performance will be degraded by the fact that people avoid uploading due to the illegality and lawsuits brought by the recording industry.