Going back to my posts there are a couple things you seem to be missing. Lets discuss the 90 H V4 vs the 115 V4. As I pointed out, most manufacturers have two, three and sometimes four different HP ratings for engines of the same displacement. It is all about "tuning" The 90 V4 may be a "detuned" version of the 115 V4 but it may also be considered that the 115 is a hopped up version of the 90 V4. Engine manufacturers design an engine based on a series of HP ratings they want to fill. So the difference in these two engines -- all else being the same except HP, means the 115 will twist a prop with more pitch than the 90 HP engine on the same boat. That applies provided neither engine is too small for the application or if they are vey close to the minimum required for the boat. In those marginal situations a 90 may struggle but the 115 would provide just the extra bit of power needed to make the boat a good performer. On the other end of the spectrum, those same two engine on the same lightweight boat may perform very close to the same.
Now back to the apples and oranges comparison of the 90 3 cylinder vs the 90 V4. Yes -- 90 HP is 90 HP but there is a big difference in displacement and that is hard to ignore. Yes - 70# is a fair amount of weight disadvantage for the V4, and the 90 may very well be more economical. But for hole shot, and overall performance I would choose the V4 if money was not an issue.