Well.... it's a long time ago since I actually downloaded some torrents with Opera (Opera Installs using the torrent)... now I am running Opera 12.17 x64 as a portable Install and all I get from a .torrent link is a saved .torrent file and the internal download manager ain't downloading the corresponding file :/ Torrent is enabled in opera:config, the preferences seem to be the same as with my old install and the only difference is, that previously (up to my XPx64 System) I only "upgraded" Opera over it's old directory and it was, so to say, a single user or one for all install - the profile where in Operas Folder, but it made use of the registry - with my switch to Win7 I installed it anew as a clean portable install and just imported (well, copied) my old profile directory to it. Be it opera:config or preferences/downloads seem to be ok to me (nothing changed, torrent enabled, open dialog as option -> but even with changing the options available I still just get a .torrent file saved)...
Anyone any ideas what I may do? Or is the torrent client disabled/cribbled within the 12.17 version?

Opera's torrent client has always been kind of helpless. The first time ever I tried torrenting at all was with Opera and it didn't work for me. At the time I assumed it was because my ISP was blocking the relevant ports, but now I know how to torrent with other torrent clients and it's just Opera that doesn't work.

Tried just now again, Opera 11.62 and a torrent file. Still helpless. I don't know what else to suggest than to try different port numbers, but in my case it's not working anyway.

Opera's torrent client was somehow never able to finish for me in the early years. It'd download up to 95% or so and then just get stuck. Somewhat more recently (in the current decade) I did manage to download a full file with it. I was already using µTorrent before they introduced it anyway, although I've long since switched to the now superior (and Linux-supported) qBittorrent.

So yeah, I don't think the torrent client should be any more crippled in 12.17 than in any other version of Opera, but I'd recommend something else instead -- especially since Opera/Presto hasn't been updated for over two years now. Since you're on Windows, a supposedly promising new client is Halite, but generally I'd recommend Transmission* for something simple that just works and qBittorrent for something with a little more options.

* There's an unofficial Windows build of it at http://sourceforge.net/projects/trqtw/

Well - ok, I really had hoped that it would be just some config I missed   , but well so I stick to my "Jockstuff" VM (Kubu LTS) for those few times I need it (like for the new Benchmark Sims Falcon Mod)