The 5.7 Litre is a much stronger engine. You will probably get better gas mileage as well. We got about 8 mpg with our 2006 4.7 Litre Tundra with our 26BH. Get about 10 mpg with our 2012 5.7 Litre Tundra with our 27 DSRL, which is 1000# heavier. Don't even think about the 4.6 Litre if you are going to tow!
2012 Toyota Tundra 5.7 Litre DoubleCab
6 speed, 4.30 Limited Slip, Tow Package
2013 Jayco White Hawk 27DSRL
2010 Jayco JayFlight 26BH sold
Yamaha EF2000is Generators (2)
1996 Honda CB750 Nighthawk