One thing to remember about all these small four-stroke engines is that they are all really succeptable to bad fuel / dirty fuel. The jets are SO small in them, they clog up very easily. So put a good in-line water separator/filter on whatever motor you buy.

Also, I've been told by my boat mechanic that the worst thing you can do to a motor is to run it at low RPM's all the time. They are hard to get the correct mixture on when they're running that slow, and they clog up with carbon and such... so whatever motor you buy, see if you can get it with a flatter pitch prop so it will run at a higher RPM for any given speed... you'll burn a tad more gas, but these things don't burn much as it is anyway.

Oh, and every time you come home and flush out your motors with saltwater, pull the fuel line off your kicker while it's running and let it run out of fuel... it helps prevent carberator problems as a result of old fuel gelling and varnishing.

I've got an old (1991) four stroke Yamaha 9.9 high thrust on my 19' Custom Weld. It came with my boat when I bought it. If I were to buy a new kicker, I might go with an even smaller hp motor, (for my boat), so the motor had to run higher RPM's, and therefore cleaner.

Just my $0.02

-N.