You shouldn't need to tighten down on any surface drive prop Garry. I often use a silicon sleeve between the nut and the prop; then screw the (nylock) nut so that the rear of the nut has just a couple of threads behind it. The only time I've ever known the nut to unscrew is if the dog comes loose; meaning that the prop spins the dog, which can spin the nut. Even then, under load / acceleration, it will tend to screw itself on, but when you throttle back, the inertia of the prop can spin the nut off. This is far less likely to happen with a carbon prop too, because they're not heavy enough. The silicon sleeve business makes it that much quicker / easier to change props (I position the dog such that the prop sits on the plain section of shaft - with the whole threaded section behind the prop), and I've never personally lost a prop that way.
I've had pretty good experiences with the Graupner carbon fibre props too, but only used them in small sizes. In the small sizes I've used (for .21 straight drive and electric), they seem to act at least one or two sizes smaller; in terms of loading, than Octura X series, so 42mm Graupner presents similar load to X437 or 438.
Just my 2p worth.
Ian