The Suzuki 100-115-140hp are the same motor. The 3kg weigh saving will be the new flyby wire saving. The Hp is just Cams and ECU.
I have the 100hp on my glass boat, I know a guy with a 140 on the same boat. The boats plate states 115hp is max.
From the info we have shared there no down side, his 140 runs the exact same fuel economy as my 100. Both are propped pretty well by the sounds.
He sort advice from the boat manufacturer prior to installation. To which I believe he got the green light.
I can get 34ish knots flat out, the 140 is more like 40.
The Suzukis are simply wicked donks, I don t think there are bad brands - Honda has 2 more year warranty, but the 140has a few extra bits over the 115 and 100 - WRT lean burn/fuel saving so think that's how the economy is so good.
Cam chain is my biggest love, no cam belts to change = massive saving if you're running the motor long term.
4 strokes feel way different, going up to 140 aint a bad idea as 2 strokes have more punch - so the 140 will actually feel like an upgrade.
my thoughts anyway