The Hellfire is a great crossover board for all conditions. I have ridden the 506 in high winds and large surf and had no issue whatsoever. It formed VERY well and I thought it excelled in those conditions. I have yet to give the 510 a try in solid surf, but I would imagine it performs quite similar as it's younger version...4" longer but not a ton more volume. The little added extra volume really helps with the larger rider and lighter conditions. I have no doubt it will be insane in higher winds and large surf.
Chop is just fine. Foot adjustment is crucial on all strapless boards in chop to balance your weight in each type of condition. They have enough weight to really plow through the chop well. I see no issues with flat water with any of the quiver.