I have the I/O (Volvo Penta with chevy Vortec 4.3 v6 225 hp) in my 18'2" deep V Crestliner SportFish which I am sooo happy with...and the kicker adds versatility. yes I have power and torque for days in this boat.
Most buy the outboards as the main engine but now that I have lived with my current rig...with my desire for versatility...the ability to do water sports all day when the kids are with me-have pulled up too 3 tubes with 4 riders behind the boat at 7000' yes, I live in the mountains , fuel efficiency, reliability and low cost of ownership (I purchased my boat used for 9500.00 with only 90 hours on the 4.3) and the ability to launch and fish my smaller local lakes when not at Powell, for me, it is the sweet spot.
I'd stay away if you want to put more than 4 people in this boat on a regular basis. It is perfect for fishing for two and sking or boarding a few more....if you need room for 8 or more I'd go deck boat or tritoon...look forward to hearing what you come up with...now off to the big lake. Ain't life grand!