Russell is a good friend of mine, as well. He is both a lawyer, a philosopher, and an SF fan and futurist, so he should have some interesting thoughts.

Festival of the Damned works great as a one off as well (I chose to run the prequel scenario the Ghoul of St Lazare first, but Festival is the real gem). Just a great bit of RPG writing.

My problem with Ars Magica is that for me it just begs for long, complex, and in depth games, which I seldom have the time to follow through on.