Tried that when testing 4.17.1

It didn't respect it very well for some reason. Maybe a bug, but if I had Limewire open at the time of clicking a torrentlink, I had to change the open using in FireFox, or it went to Limewire instead of Azureus.

Maybe that's fixed now?

Edit: on second thought, I don't think I reverted to default... not sure, but when asked, if asked, when first using it. There is no way I would choose yes, as I hate the torrent part of Limewire.