"Mark, you will get decent arg
"Mark, you will get decent arguements from both sides. Only you can decide what fit's your requirements and pocket book.
And I will compare "new" motors, because used opens up many cans of worms on both sides of the arguement.
Here's my 2 cents (and I'm an outboard guy).
Dollar for dollar you can get significantly more horsepower for your buck with an inboard/ouboard set-up.
If you do some looking you can get complete volvo/mercruiser engine (4.6/5.0/5.7) plus the outdrive for about 8000-10,000 bucks. That will give you 200-300 horsepower depending on configuration.
Take a Yamaha 250 horse 4 stroke outboard as an example - the list price is a few bucks shy of $24,000. The direct injected 2 stroke model sells for the same price.
However, as you will see below, you will need significantly less horsepower from an outboard (in some cases) to achieve the same performance you would get from the I/O.
Even dropping to a 150 horse 4 stroke or DFI you will still lighten your wallet by about 15K give or take.
So for price - the I/O wins that round. And that's why so many smaller cruisers/bow riders etc are mfg with I/O's - the builder can get them to market with a lower initial cost.
Overall weight. A 250 outboard will tip the scales at a little over 500 pounds (depending on mfg). A 5 liter Mercruiser with an Alpha or Bravo drive weighs about 1000 pounds. A 150 outboard will still come in the 400 pound range.
The new Yami, V8, 350 outboard weighs over 800 pounds and sells for 35 grand, but that's a whole different "class" of motor - but may be what you are after?
However, there is no general restrictions on how much I/O horsepower you can put in a given rig. With an Outboard, the transom can only take so much weight and stress, limiting what you can hang off the back.
You will get arguements about what is easier to work on. As you get older it's alot easier to get at an outboard which is hangin' "right there" compared to an I/O which may be burried or partially burried in the floor. If you are taking it in for service, then you have no concern in that regard. You will pay 100 bucks an hour plus to have them worked on.
Which is cheaper to maintain? neither, this is a marine product, you could feed 3rd world nations for the cost of servicing either
What kind of performance can you expect. Here's a couple of new, actual "on boat" tests. I picked similar hulls (23 footers) one with a 150 horse Honda 4 stroke outboard, the second with a 260 horse, 5 Liter, multi-port injected Mercruiser and the 3rd with a Mercury 150 Optimax, Direct Injected 2 stroke outboard. That will give you an idea of the speed/gas consumption between the three "main" market options.
The dry weight of the boats compared was 3700 pounds, plus the motor weight, plus gas/batteries/stuff/passengers etc etc for the 4 stroke and the I/O - the Opti results were from a model weighing 800 pounds less (dry weight).
Summary of the results - basically, they all suck the same amount of gas. The top end speed of the 4 stroke outboard sucks compared to the other two.
Both the 4 stroke and the I/O will have significantly greater maintenance requirements than the DFI, but if parts go bad they will all cost you major dollars to repair.
So the answer is - whatever suits you."