Maybe I should wait until my second season, but I just can't help myself...
So far the only problem I've had is the boat stalled since the day I picked it up. It took me forever to get the dealer to stop telling me I had to warm it up more before their mechanic finally fixed the problem with a simple carb adjustment. Since then it's been problem free and I've been very happy.
This is our second 3.0, but we rarely have more than 4 people on the boat. Usually it's just me and my wife. If we had any intention of having more than that on a regular basis there's no way I would have gotten the 3.0. (or a 180 for that matter)
I will say though that a few weeks ago we had 4 adults in the boat and pulled a 5th on a tube and didn't have any problem getting up on plane. All in all it's a pretty impressive little motor, but it has it's limitations and it's place.
With all that said it sounds like you've had more than your share of problems. Sounds like your dealer should prep his boats better because none of those problems should have happened and they're definitely not the norm for a FourWinns boat.
Hope things go better for you for the rest of the summer. (right up until hockey season

)