If I may, allow me to tell you my first pontoon buying experience.
We did our research like everyone, went to boat shows and burned up the internet.
It came down...for us....to purchase some model of Crest. We liked the Crest brand because basically they were very solidly built. Should last longer than the average pontoon boat, but because of its robustness, it would be slower on the water. For me not a problem. I still do not understand the speed freak syndrome when it comes to pontoon boats.
If you pick a specific brand you then have to ask yourself, who sells that brand within driving distance of where you live? Now remember, for some people who are very fortunate to live on a lake and have a dealer come pick up the boat for service or winter storage, they are truly lucky. I have no house by a lake...have to drive a minimum of 1 3/4 hours to the closest lake....launch and recover every time out....and drive back home.
We found something MORE important than the boat model was the dealer. Our dealer turned out to be less than honest, a bait switcher and I would not recommend him to my worst enemy. Therefore, I certainly don't take the boat to them.....by the way 3 hour drive one way....for anything. FIND AN HONEST DEALER !!!!
You will find that not all dealers can service all motors. Where I live there is no authorized Suzuki mechanic. There is a mech that work on a Suzi but I don't believe he is certified. For that, a 4 hour drive one way. I find that when I call other Crest dealers they are all nice on the phone until they discover I have purchased elsewhere and just need help. I never get a call back with an answer to my question.
Look very carefully where you live, who near you sells pontoon boats and what kind of reputation do they have. Call them anonymously with a question telling them you didn't buy from them and test how they react.
As for Merc motors.....lots out there....lots of support out there. I have a 22 foot tritoon with a Suzuki DF 150. At around 5500 to 6000 rpm I can hit a little over 40 mph. Do I run it at that??? Heck no. The only time I go fast is if a storm sneaks up and I need to get back to the dock asap. I normally run from point A to point B at 20 to 22 mph and that is plenty not to mention it conserves gas....which aint cheap!
Wish you the best of luck. One thing we wish we had done diff on our boat. It had full wrap around lounge seating along the edges with 2 Capts chairs. That left NO WHERE for coolers yada yada. Think about what YOU are going to do 85% of the time.
Will keep watching this to see how it goes.