They are a lot easier to set up -- it's a lot easier to tighten the cable with the fixed bolt. They're wider than most carriers, which translates into a bit more leverage (or mechanical advantage) , which "might" be good with certain aero brake levers (making sure you have enough lever pull), but it is not really that wide, and adjusting the straddle cable height up or down will in most cases have more impact on the amount of mechanical advantage.
I do have a set with Suntour XC Pro Cantilevers on my Toyo Atlantis -- they're nice and worthwhile, but I got mine for about $25 used, so... :)
Julian Westerhout
Bloomington, IL