In my opinion, neither! Suzuki all the way!
the Verado's cost a bomb more to buy (and run! I've heard of fuel consumption nearing 30gph) and really don't offer anything over the Yam or Suzi in performance to justify it.
The yam is great, but again is more expensive than the Suzi- which is a much smaller physical unit as it is a 55 degree v instead of 60. It is also a new addition to their range this season, where as the Suzi has a couple of years under its belt.
As for weight, the merc is so much heavier- even with a much smaller displacment!
Suzi- 3.6lt 263kg
Yam- 3.3lt 272kg
Merc- 2.6lt 294kg!!
I have been out in a 9.5 with twin Suzi 200s and it went awesomely! Just lacked top end- 50kts as I remember. (owner couldn't afford the 250's). In fact it went just as well if not better than a same size humber with 200 e-tec's. A 9m with twin 250's would be spot on.
I have a Suzi 250 on my 7.5, and I wouldn't change it for anything!! Apart from when they bring out their new 300(+)?? outboards next season (supposed to be a v8! and if mr Natwest will let me, I'll be ordering 2 of them!) I'm even getting a better top speed than an identical rib with a 250 2 stroke.
I know it doesn't answer your question, but I think you should definatly consider Suzuki's!
Drive it like you stole it!!