Yeah I hope so to.
Seriously though, from my own experience I can tell you I *did* notice a difference in runtime AND performance.
I have a Traxxas Bandit and Rustler, I used to have Tamiya connectors on both, the Bandit running a 12t motor and a 15t motor in the Rustler. If I ran them on 7-cells, or ran them at higher gearing, the connectors WOULD heat up a lot, OR they would simply heat up anyways and melt together if I ran too long of a time using 1800 or 3000mah batteries. After I switched to Deans, I noticed the same batteries gave me better runtime (went from 8-9 minutes to 10-12 minutes) AND I had better overall punch and top speed (I could just about tell), without the fear of melting connectors if I popped too many wheelies or gunned the trigger hard too much.
So bottom line is yes, if you want better runtimes, and you think you want some speed, OR your connectors heat up every now and then, then go ahead and upgrade to Deans. I mean you can also argue why upgrade to from bushings to ball bearings, too, right? It's simply more efficient. [8D]