I chuckle at some of the weight "savings"...For example, when I'm buying a saddle, the last thing I consider is the weight of the saddle. Trust me, with my tush, a savings of 150g is just not going to be noticed

That said, I can see a difference between riding my 30lb hybrid and my 22lb road bike. However, it isn't the weight, it is the hybrid tires are heavier and have more rolling resistance.

The weight tends to only be a penalty climbing and starting up. Once you're moving well, it is the wind resistance you are fighting. The bicycle's greatest adversary is slicing through the air and, well, it isn't so much the bike that gets in the way as the rider.

Even with respect to climbing I read a statistic that said that a 5 lb weight penalty adds only 30 seconds to a 5km climb at 7%. If you're a racer, then playing weight games make sense. If you ride for enjoyment, find the bike that fits and you like to ride and, when all things are equal, then choose the lighter component (e.g., han-grrl's suggestions).