I saw a twin Suzuki 140 4s setup on I think it was a Zodiac rib at the boat show - the chap had both engines running, and you couldn't hear either.... just the trickle of water idling out the back.
Yes, the 140 is lighter than the 115 and 90 - the extra longshaft 140 engine is 191kg, and the extra longshaft 90 and 115 engines are 194kg according to the brochure I picked up from the stand at the boat show.
I haven't as yet heard anything particularly bad about them, which is why I'm hoping to have a 140 installed on a new Humber 6m rib which I am hoping to purchase in the next month or so
-Alex