It's true that the bigger axles are heavier and take a little more power to turn, but so is the tire you're putting on them. When you consider that these are c-clip axles, you're playing with fire regardless if you're on the street or 4 wheeling. Take a look at the Interco website. The differece between a 33 and 35 can be as much as 20 lbs different, depending on application. Now consider this, the 35 can be as much as 50lbs heavier than the stock rubber that came on these trucks. That's alot of rotating mass.
http://www.intercotire.com/tires.php?id=9&g=1
At the very least, a 14 B semi floater in the rear would be some added insurance. It fills the gap between the stock 10 bolt and the Full float axles without being too much.