"David, you have heard correct
"David, you have heard correctly. In almost any comparison you can make the two stroke will outperform the 4 stroke.
With the two stroke, 150 in this case, every 360 degrees of crank rotation is driven by six power strokes - all 6 cylinders have power every rotation. It's 4 stroke cousin will only have 3 fire per rotation because the other 3 are exhausting.
Given that the motors are nearly identical on displacement you can do the math. That's why the 2 stroke will get out of the hole, up on plane significantly quicker than the 4.
Additionally, despite all the hype about how much more fuel efficient the 4's are, the actual test numbers from "real on water tests" do not exactly pan out.
Yamaha is definately better in that catagory than all the rest, but for the most part test results have shown the 4's to be less than 10% more efficient in the "majority" of cases. And yes I have the numbers - recently posted quite a few on the OMC section of this board.
Once you add in all the "extra" maintenance required by a 4 stroke, the actual operating costs tend to leave the 4's more expensive to run.
And yes, the 4's are quieter. But again, not to the degree they are "hyped". A 2 stroke at 3/4 throttle produces the same DB reading in the cockpit as a 4 at WOT - so not really the earbleeder the salesman would have you believe.
I am not saying to stay away from 4's, but don't go in blind. They need to be diligently maintained - think of the schedule in the owners manual as the absolute minimum (I recommend twice the interval for oil/filter changes, valve adjustments, belt adjustments etc).
A 4 stroke doesn't like to sit around for months on end and then only be run for a few hours on a weekend. But if you are willing to care for it, it may well last a good few years.
Unfortunately, they have not been on the market long enough to really get a good sense of their lifespan. We know you can have a 30 or even 40 year old 2 stroke still working fine, it's far more difficult to find a 4 stroke out there that's even 10 years old - so tough to form an opinion.
If you think you will be happier with "2 stroke" performance, you always have the option of the Direct Injected 2 stroke motors. In most cases their initial cost is slightly lower than a new 4 stroke, they are just as environmentally clean, fuel efficient, quiet etc etc and will kick the snot out of their 4 stroke counterparts - just like their older cousins...."
A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it :)