I have walked on my SS deck @180lbs and it doesn't even crinkle. I usually try to slide on a hip or butt down the lattices the run underneath where I assume it's strongest. I only do it when there no risk of me falling on it or having a wave bounce me and cause extra force.
I think the ratcheting case of the 2.5's makes the biggest difference. The 300xs with a 3.0 sportmaster and the bigger props needed for speed with the low limiter would be a recipe for hooking on an ss.
Other than the limited choice colors, allisons probably have the best gel on the market. Most boats sit in the mold at least a week to cure, as opposed to a couple hours for some other brands. Have seen many allisons here in the Midwest that sit in barns or under tarps at 0 degrees all winter...
It is often done for both. At high speeds the stock holes can let in too much water and WP can get too high. As an added bonus, plugging a starboard hole streamlines flow to the thrust side of the prop which sometimes results in a speed increase
Our's carries weight pretty well. They are a very easy prop to drive. It may or may not have the blade area to carry your o3 if you are loaded heavy. Try to leave all the meat on them if you get one cut. They can be prone to cracks if they are thin, since they are cut down choppers.
It's probably preferable but they are very pricey. From a performance standpoint they do very little. They get your center of gravity lower, other than that they just look and sound cool.
The mercury "WOT throttle" is 6500 supposedly, but the rev limiter does not kick in until 6850. The rev limiter limits rpm by adding extra fuel, so sometimes you can even go above 6850 if you can burn the fuel.