Will a Ford F-series pickup haul two 300 pound people? Of course.
Will a Ford Festiva haul two 300 pound people? Not comfortably.
Which will still be operational after 25,000 miles of hauling those lardos?
The P-series pistols were built to take the punishment of hot ammo. The SR9 was designed as a light, compact 9mm. Both will fire the +P+ ammo, but I doubt the SR9 will hold up to much of it.