I'd say stay on the N20 or go N20C. F18 is a non starter for you. I've raced that boat heavy and it does not work.

I'm not sure how the N20C will go with that weight either. I would think light is fast on a boat that has to lift the weight out of the water.

I'm still on my N20 and still love the boat. I wouldn't buy a new one but like the one I'm on.