The article linked below does a good job of analyzing the critical areas for improving speed on a bike. It notes that a speed suit provides more benefit than a specific bike frame, that a helmet change actually does make a difference. Interesting read.
However, what isn't mentioned is that the importance of consistently maintaining an aero position trumps ALL of these components (combined). The article (appropriately) assumes that the reader already knows that aero position provides the biggest, most significant way in which to enhance speed. Unfortunately, knowledge and application are two entirely different things. Yes - all triathletes and time trialists "know" we need to get into aero as much as (safely) possible. However, both data and experience tell us that outside of the pros, it simply doesn't happen consistently.
The single greatest benefit of the Aerobar Edge is that it reveals the truth. It's a "lie detector test" (or at least a "perception/reality detector test"). There's a big difference between "thinking" I maintain an aero position 91% of the time and actually demonstrating that objectively. And once it's being monitored - it is certain to be enhanced.
So read the article and take note of what we can all do to get faster. But remember - each of these is of little value if we're not maintaining an aero position - consistently.