I'm sure there are people out there that have used either of these or if you know of something else that is better. -I have not used both, only the hook and quick release hook.
I think I'm leaning towards the key hole system (Item G) because I feel it's safer than the hook. -With a load on the attachment point, in an emergency situation, the quick release would be easiest and the safest.
I'll probably end up punching a hole in my hull, or tearing the tramp with the hook. -Always a possibilty, a hook is inconvient when pulling yourself back on board after a capsize, in that I'm wanting to twist my hips to one side while lifting myself up to avoid contacting the hull with the hook.
I know I won’t be going with a “nappy” style, just looking at the design of these it is clear that as a guy they’re not going to be comfortable. -My oldest son (mature) and I both prefer the nappy harness. We have an older harness with the leg loops and both feel uncomfortable in it, compared to the nappy. The spreader bar eases the hip squeeze, but can be uncomfortable while sitting or crawling. Our nappy's are one size larger than "perfect" allowing adjustment in the straps to get a proper "home" for the spreader bar.
No help since we're not in your area, but yes, definetly go try stuff on.