you should be right with any normal sized fish of say between 20-30kg but beyond this, well, I think you're right. If you hook a 40kg + fish on this rod, then be afraid - it's going to hurt. If I was you, I'd think 10-12kg of drag and no more than that.
I have just purchased a Ripple GT 78XH after owning a GT 78 flex and loving it. But I feel quite scared now all 64kgs of me. Sounds like this Fiji trip in November is gonna hurt bad.