I have never understood the level of animosity that is directed at David Watanabe. Yes, he used libtransmission unattributed in an early version of XTorrent, a situation which he remedied pretty quickly. At its core, this is a licensing concern and IMHO does not justify the level of anger directed at this developer.
I'm writing this comment to clear up some of the blatant mistruths being spread by Watanabe detractors on this site and others. I'm not affiliated with this developer in any way, but I have a real issue with this kind of misinformation.
First, XTorrent has always worked well for me. I purchased a license for the product because I appreciated how polished and well-integrated the application is; I support shareware applications, especially when they are well written. I have never experienced the kind of instability that other users have claimed, even when being used heavily.
The upgrade path for XTorrent is clear and well-documented. If you purchase the basic license, you will be paying full price for major new releases. While it would be nice if the author provided discounted upgrades, he is certainly not required to do so.
The "Family Lifetime" and "1-user lifetime" licenses allow free upgrades for all new releases. My 1.x family lifetime license code worked just fine for the 2.0v83 release, and I have access to all "pro" features of the release. I did not, as some users have claimed, have to "pay again" to use my license code. An informal poll of several acquaintances who also use XTorrent revealed similar results; in fact, I was unable to find anyone who experienced difficulties using their existing licenses with the new version.
XTorrent is not a "ripoff" of Transmission. The 1.x release used the open-source libtransmission library, which is a core set of libraries provided by the transmission authors SPECIFICALLY FOR THE PURPOSE of creating alternative bittorrent applications. This is NOT stealing! It is using the library as the authors intended. Watanabe's mistake was not in USING libtransmission, but rather was in not clearly stating that XTorrent used the libraries. This is not that uncommon a situation - XTorrent is hardly the first application written which got called out for lack of attribution.
XTorrent 2.x no longer uses libtransmission - it uses a new mac-native Cocoa library called "XCore". Time will tell whether private trackers will have issues with the new release, but the new release doesn't appear to be affected by several private tracker's ban on transmission-based torrent clients.
Are there other, free bittorrent clients available? Sure. I find them to be clunky and awkward to use, with inconsistent, poorly designed user interfaces, but to each his own. I do occasionally use Azureus as well, typically when I have to download something from a private tracker which blocks transmission-based clients.