As I read before,some other users also suggested this.Please make Tracker Exchange selectable again,at least from the special section with default-off.
It was a very useful feature of libtorrent,when downloading not so popular torrents with only a few peers,even when DHT and PEX couldn't find any.It has it's own problems as we know(tracker multiplication with the slightest difference in the url,etc),but it made some of our jobs easier.
It would be awesome to see the possibility to enable it again!