Alot of rebuilt motors are from the southern salt water states. Not uncommon for Florida boats to see 500 hours a year as the hard core guys go out every weekend that it is not howling, and then often 20 miles off shore to get to the fishing, or more, and then back in.
The repowered engines do not have much work done on the leg unless a seal or lower bearing goes, which is not very often. The companies that do these power heads are doing it quick and dirty and expect no failures for any short warranty.
My experience with a 1992 Johnson 120 was terrible as the frankensteined engine had carbs from three different engine sizes on it, and it ended up having to have all carbs taken apart and re jetted. End product was good, after a year of misery with a shop that was not equipped with a dynometer. Different shop figured out the problems with the carbs, but took $1500 to do it. Not much saving at the end of the day for the amount of grief I suffered with it.
Drewski