Using "light" as the hallmark only tells one part of the story. High end bicycles of modern manufacture are all pretty close weight-wise, but what really matters is the quality and sophistication relative to the sum of it's parts.

Example- Somec carbon frame, and Super Record 11 with top shelf carbon/tubular wheels, is night and day different than a 105 equipped generic LBS bike (Trek, Specialized etc.) The difference in the ride is so substantial, it will blow your mind.

I can definitely feel a weight difference, but only if that difference is accompanied by a superior groupset/wheelset.

So yes, equipment does matter.