Folks,
Just a quick update to let you know that today, I had the RE drop brackets installed.
Although I haven't done the alignment yet, it looks as if the steering vibration is gone. I am not sure however, where my caster is at the moment. My lower arms are a bit longer than the ones RE suggests (16.325" vs 16") while we adjusted the uppers at exactly 15" (which is the recommended by RE).
The interesting thing is that at these settings and with the new positions of the arms, the vibration seems to be (almost totally) eliminated. I'll try to verify this tonight, but that's what I noticed while driving from the mechanic's place to the office.
Wish me luck