Get an IR2235 and you will see the need for 1/2 in those bigger sizes.
I dunno...I'm looking into 3/4" Guns now...eying the 2145 or the 2161..or possibly an offshore...going down that road for the big boy stuff and then getting one of the small compact 1/2" guns like a MG3255 or the AWP050C for day to day....stick with my M18 for 3/8"
My mode of thinking is on large sockets like that, there's no need for me to have both Chrome & Impact, Deep And Shallow like I/most people do in 3/8 and 1/2" drive...so from my understanding, the effective torque limit for 1/2" drive is ~850-950 ft/lbs of torque...that's NON-Impact torque.. so if I have to crack off a crazy nut which even a MG725 cant handle, I Then need to bust out the ol breaker bar and cheater pipes, but would be limited to less then 1,000ft/lbs by virtue of the drive not being able to handle any more. Going with 3/4" Drive, you raise the ceiling of effective torque capabilities...I have not sheared off any drives...
Running them in an impact...when I use 3/4" Drive sockets in my 1/2" gun...it hits just as hard, sometimes seems like harder...IMHO it duplicates the power sockets like the 19mm Lisle 77080 socket...increasing the socket mass directs more impact energy to the fastener...3/4" sockets (size for size) are much heavier then their 1/2" counterparts. on impact sockets, Heavy = Good thing.