Most reliable hp & torque for x15

[tree98]

Spec'ing a new truck with an X15. I know I read somewhere on this forum what the best rating is for an x15. To high and it's prone to liner fretting. This truck is 80k-90k gross and goes off-road. Peterbilt says get the 565 hp 1850 torque because it's only a few hundred dollars more than the 525hp and can easily be turned up to 605hp. I wouldn't want to go to 605, originally I just wanted 525. What would be most reliable? Gonna have 4.10 and an 18 speed 24.5 rubber