Straight bars or Drops, that's the dilemma. Which is more comfortable? I'm looking for the occasional cardio workout or commute to work (6 miles). But it's got to be a comfortable ride because of a chronic lower back condition. I don't plan on any one outing being more than a 15 mile trip. I've been looking at the Trek FX series (7.3 and 7.5 with straight bars) and the Trek Pilot 1.0 (drops). Havn't had a chance to test ride either one because on the day I looked at them I could barely walk. Any suggestions or recommendations would be greatly appreciated.