I recomend that you roll a release based off the latest RC_0_16 tree as it going to be awhile before libtorrent 16.9 is released
libtorrent svn is fairly mature I see no issue with running rolling-builds with every QBT release
it would be far better to _always_ use the latest rc_0_* tree if the last libotorrent release was >3 weeks ago
its better to have the occasional lib-torrent bug then to be using a outdated version of lib-torrent that may be seriously broken