You're right about the Madrid event... I didn't even knew of it until april. Had I known it beforehand, I would have endured 5 hours of road trip (I just hate planes for in-country flying) just to take part.
As for the other viral events... if you look closely to my avatar, you'll see I'm proudly wearing my Encom badge (I'm still waiting my Flynn Lives and my Space paranoids pins, but spanish mail is slooooooow).
Of course, I'll take part in any further quest Flynn lives (or any other Tron related organization) will do.