Worth for money to go the next level up in components?

In terms of performance, the gap between Shimano Dura-Ace and Ultegra is smallest, followed by that of SRAM Red to Force, and then Campagnolo Record to Chorus. Top-level parts use bearings instead of bushings, and have better finishing and materials.

Dura-Ace, Red and Record offer lighter weight and fractionally faster shifts, with better feel at the lever.  Often, in a company's line of bikes the price difference between the top two or even three models reflects upgraded components, wheels and other parts--the frame may be exactly the same.