I have a 2011 5 HP 4 stroke Mercury
25" shaft which is basically the same engine
and at 10 years old no problems so far.
I have replaced the spark plug
one time and the fuel filter
one time. Impellers every couple years and oils yearly and it has been great.
I've even motored back 25 miles are so across the Bay when necessary several times.
It pushes my 6600 lb Bristol 27 quite nicely.