Deans is one of the most widely used connectors for RC. The Traxxas connector is simply a different brand. They both claim zero loss. IMO the Traxxas easier to solder and a bit easier to disconnect than a Deans because it's a little bit bigger. The other advantage is that no heat shrink tubing is necessary with the Traxxas. The disadvantage to the Traxxas might be that not a lot of people use them, and if you had to borrow a battery or a charger, you might have to use an adapter or simply be outta luck.
Personally, if all my stuff weren't Deans already, I'd think about going Traxxas, just easier to use in general.
Hope that helps!