[THEFERMANATOR]

I/O's are fine for there application, but not the best for a boat that stays in the water for extended periods. The big outdrive killer is outdrive corrosion in the exhaust cavity from the inside out. Unfortunately you can't get in there to paint it or protect it since it is unaccessible. Also you have dissimiliar metals constantly submerged in saltwater. Outboards are easier to maintain as they can be trimmed out of the water and don't have to stay submerged in it. Up until DFI's and 4 strokes, the choice was easy for economy until recently. Now outboards are pretty much dominating most categories. On a V-21 though, you only have the outboard option due to the built in set-back.

And WILLY makes a good point in regards to current technology, they have gone the way of automotive and have become to complex for the average shade tree to work on. Even doing a tune-up now is involved since indexing is required for electrode clearance and proper burn. N/A 4 strokes have a slight edge in not being as complex, but not by much. And as emissions get more stringent in 09 they'll only get more and more sensors to contend with. And the rumor is by 2012 they'll even have catylic converters in outboards, possibly even sooner as MERCRUISER is already working on prototype cat converters for the 6.0L I/O there working on.