Originally Posted by Nagrom_

The 105's have a steel shoe plate. The R540's have a plastic one. Shimano considers both of the shoe plates a "consumable" part. The steel plate is never going anywhere. The plastic plate on the R540's doesn't last too long. The R540's are modeled after DA's, while the 105's look more like ultegras.

I mainly went with the 105's instead of the R540's because because of the steel shoe plate, and never having to worry about it. It was worth the $20. and they're shiny.