it'll help the towing manners, but there are a lot of other issues you'll need to change in the computer, such as speedo reading. it won't change your capacity, as legally it is governed by the GCVWR from the factory.
to see what it'll do, try a set of smaller or lower profile tires in 2wd mode and see what it does. yours is an all wheel drive trac, so you'll have to find 4. cheaper to test this way than to change the gears front and back
I wanted to bump my gears up to 4.10, but my reasoning was to get the cruise MPH up into the 3100+ rpm torque band. my 2002 V6 really tows well when the engine is up in that range.