I'd like to thank you all for the interesting suggestions, I'll carefully evaluate all of them.
I must also say that in the beginning I also had thought at a rtorrent+tmux+pf+scp solution, but it looks like getting way too complicated/time consuming to get everything working in the right way. Especially considering I'm a pf rookie. Bitflu and btpd look promising, but are way lacking some of the key features I need. Till now it looks that transmission has an edge (suporting everything out of the box with no fuss also including encryption and DHT), but I'll also have a look at the CPU occupation, which, on a 200MHz client, becomes key.
