OK well this has been hashed over pretty good but I will add my two cents worth. I have been a boater for 50 yrs, mostly outboards on smaller boats. OB were great, easy to work on but replacement parts are quite expensive, my last OB cost 235.00 for an enrichment solenoid (choke), same thing on an I/O was 25.00. Now that I have a larger boat I prefer the I/O, but I can do most all the maintenence myself. Yes the I/O is more work to winterize but easier to make repairs and parts are cheaper. If going small (under 100 hp) consider an OB, if going bigger then consider the I/O. Fuel economy will be much better in the I/O, but performance would be better in same size OB. Here is the real consideration......what if you have to replace (repower) your boat?? My 140 hp new in crate from Mercruiser is about 7000.00, now go price a new in crate 140hp OB......OB will cost about half again or more than the I/O, probably around 10,000.00 or more. Yes the laboe will be more to swap the I/O than an OB but not equal the total cost. As stated my many others it comes down to a personal preference, in my case small boat go with OB but if looking at a motor over 200 hp then I would definetly go I/O. Just some food for thought!!!