I've never understood the "re-powering" argument. It typically takes me about 15 minutes longer to pull or reinstall an I/O than it does an outboard, not that I've ever been in an emergency rush to do either one. The I/O requires that you pull the outdrive (6 nuts), and take off the exhaust hose clamps and water feed hose clamp that's not required on the outboard. On an outboard you've got to disconnect and reconnect the steering that's not required on an I/O. Disconnecting fuel lines, throttle, electrical, engine mounts, and hooking up hoist chains is about the same on both. If you're in some kind of "Indy 500 For Engine Changing" maybe that half-hour would be a significant benefit.
Do you really think you can rebuild an outboard faster than an I/O? Machine shop time (boring cylinders, rebuilding heads, etc) is the same on both (actually probably quicker with an I/O since you can get them done literally anywhere), and parts shipment (pistons, cranks, etc) is the same - the mail doesn't deliver OB parts any faster than I/O parts. If you're looking for used parts, there's no comparison - the auto junkyards are full of potential I/O boat motor parts ......
If you're talking about swapping in a different engine, OB or I/O, you're back to nothing more than the half-hour time difference. Cost wise, it's going to be an expensive half-hour though. A re-built OB powerhead of over 100HP will typically cost you at least twice as much as a re-built I/O motor. You'll see about the same difference price-wise ordering parts if you do it yourself. And if you're talking about new motors, the outboards with HP in the typical I/O range will cost you about 3 times as much.
If you're chasing fish, an OB is great. If you're into other aspects of boating, it's hard to beat sunpads, swim platforms, and bikinis ......
