Oddly, Bigfoot brags about how FN Torrent has zero impact on CPU utilization and online gameplay, but the company doesn't explicitly mention whether the client affects pings in online games. And even if it doesn't, some users might not be too thrilled with having to use an external hard drive or USB key. Still, the FN Torrent client is a free download. It joins Bigfoot's FN Firewall, which is based on the iptables open-source firewall that comes with some Linux distributions.
Update from Scott: I don't see what's odd about Bigfoot's claims here. Sentence two of the press release reads: "With FN Torrent, gamers have the power to download the torrents they want without impacting their online game play." That seems fairly unequivocal to me. When I spoke with Bigfoot CEO Harlan Beverley about the BitTorrent client at GDC, he made a similar claim to me in person. We didn't get into the nitty-gritty questions about client-side packet prioritization versus global network performance, in part because I didn't care to argue and in part because we can (and intend to) test such things ourselves. At any rate, we can certainly know more specifics about how the client and NIC handle these matters by asking Bigfoot about itand we have done so. We'll have another update when we get some answers.
Update 03/22: A spokesman for Bigfoot has responded with the following statement:
[FN Torrent] does not negatively impact ping in games at all.
The only time it might is if the user’s bandwidth on his cable modem was exceeded, and for that FN Torrent has bandwidth controls.