Not exactly a huge difference on a 3/4 ton truck... Choice wheels and tires makes more of a difference
Dropping 50-odd lbs off the rotating mass is like having one less steel rim installed.
So yeah, it's significant.
Most especially to acceleration and MPG.
Braking performance between rear discs/drums is pretty much moot, more so with an effective ABS or RABS.
A truck that spends significant time buried up to it's rockers in mud and such can benefit from discs, which are (for the most part) self cleaning.
Drums tend to fair better on a road vehicle in a corrosive environment (IE: salty roads, etc).
Drums make it much easier to incorporate a parking brake. Important if you have a manual transmission or annual vehicle inspections.
Vehicles that tow and make heavy use of their brakes can benefit from discs as they shed heat faster and are less susceptible to fade. They also recover faster from fade due to aforementioned better heat shedding. Yes, OTR trucks predominantly use drums. That's a whole different kettle o' fish.....
Whether or not it's worth the hassle and expense to switch from drums to discs on a regular use pickup is completely dependent on the individual owner.
Then there's the guys like me have already "optimized" wheel and tire selection and just can't leave well enough alone, although I'll likely leave the drums be as they fit well with 90-95% of my usage.
But there's always that little guy in the back of my brain whispering: "Dooooo Eeeeeeet, you know you want to".....
