A few things I see in this thread that could us a little more discussion......
As far as adding weight to the stern to make your boat faster, well it's not so much about adding weight as it is about moving weight and or balance. A lighter boat with the same weight distribution is always faster, that's just physics. shifting weight from the front to the back is more of a balance thing and allows the the bow to run higher and more of the hull is out of the water in-turn leaving less surface drag. Just watch a few tournament take offs, windows latched open, partners sitting against the motor, anything thing that creates wind resistance is on the floor or in a compartment, and no extra seats or gear that isn't necessary (trim weight!). I always get a chuckle out of it because hull design still plays a roll in speed and there are a few factors including hull weight, hull lift, hook, and if it has a pad to run on which is more of a bass boat thing. Our our walleye boats don't have a "pad", they all have some form of dead rise to the to stern of the boat. Bottom line, hp for hp, the same brand boats are always at the front, the rest of the tricks are what separates those to squeak out that last little bit. Want to break 50mph, find a 60 degree day with 20% humidity, leave the windshield open, and take off your TM and TM batteries and let'r rip tater chip. That last few tenths of a mph will be there so long as you don't hit the rev limiter of your engine and you have enough prop.
Second thing, the reason we all see better speeds in the afternoon versus morning is 100% based on humidity. Think of it this way, in order for your engine to run, the pistons compress a specific volume of oxygen and fuel. To an extent, when you add more air, you can add more fuel, and in turn make more power, hence why super chargers and turbos work so well. Ideal Air fuel mixture for a gasoline is considered stoichiometric mixture at 14.7:1. When there is humidity(water) mixed with the air, it's taking up space/volume that could otherwise be oxygen therefor you have less oxygen to complete the combustion cycle. Couple that with the computers that run our engines and monitor exhaust, it will automatically lower the fuel delivery to get the right fuel/air ratio and now your making less power and therefor running slower. You'll make the most power with cool, dense, dry air.
Also be careful when comparing hull weights. There is not industry standard for how to weigh or what is on/in the boat when it's weighed. You'll find a lot of variation in "dry" hull weights between manufactures. For instance, one may do it without the windshield and the other with. When I compared all of the 21 1/2 ft boats 2-years ago there was almost a 1k lb difference between the lightest and the heaviest. Is there likely a difference, absolutely, I just don't believe it's 35% between one and the next of the same size and same hull materials.
Last thing, sign me up for a test drive on that 450R tiller!