U2 will NOT add support for new versions of Bittorrent clients immediately. The reliability of new versions need to meet the high requirements, and it needs time to be proved.
Thus, all new versions will be banned by default. Staff will add support to/unban them after a period of time if no serious problem is reported.
It's strongly recommended that DO NOT use the "Check for updates" feature of ALL Bitorrrent clients. Bittorrent Protocol is about 15 years old, which means you can hardly receive any useful feature updates or bug fixes from new versions of the client. Especially uTorrent, whose new versions were mainly focused in MORE ADs and useless multimedia features since uTorrent 3.3.
We recommend uTorrent 2.0.4 and 2.2.1 to all users who need extreme performance and reliability. Those two versions are more stable than all uTorrents after 3.0, and have less ADs.
We recommend 3.2.3 to users who need to download/seed mega torrents like TLMC. U2 has less than 10 torrents of this kind currently.