I have a 200hp v6 Merc Verado on a 24’SSBXP SPS. I am 40-43 mph with 1-3 people and half tank or less of gas. 37-38 mph with a FULL load of people and fuel. IF the Yamaha 200 hp was v6, with all that added torque all the way through your power range, I’d say stick with it. The 100lbs of boat + extra weight of SPS+ is going to offset some of that 50hp gain. However, I am a bit less sure with the v4 200hp vs. v6 250hp Yamaha. For me it may be less of an overall horse power issue due to weight trade offs as much as is it v4 vs. v6 torque, improved hole shot, and smooth speed increases throughout the power range. Tough one you got there, but in the end I just really don’t think you will see too much difference in top end speed. I think you are likely to just see an improvement in hole shot when loaded up. However, how much do you want to hammer it from a dead stop with a boat load of people anyway?