I love my 3/8. Variable speed is a big plus, the light is handy, and the tool itself gets into some tight places. If you overload it or stall it by manually torquing it with the trigger pressed, it will shut down in a couple seconds to save the motor/battery, so there is no risk of damage. Let go of the trigger and re-press it to reset.
The tool is rated for 35 lb/in (I think) and I am willing to believe that is correct. Being a ratchet, if it overloads, you give the handle a tug. How much brute force the handle can take I am uncertain. The "head" of the tool is solid metal, and it extends internally up to the vent holes where the rubber grips start (about 2" hidden inside). After that, it's plastic, but rather beefy (yes, I took mine apart to have a peek).