The question on how good lawnmower engines are would be better answered by asking how well will the operators take care of the motor. There are three components to longevity when it comes to any gas engine. First is using good quality oil and never going past service hours. Second would be the air cleaning system, motor manufactures have really improved this with inner filter systems, it doesn稚 matter how good your motor is if you breath dirt. Third is cooling I have replaced more low hour motors from operators not keeping debris from clogging the cooling fins around the cylinder walls than you could imagine. Although there are better engines than B&S out there through good servicing I have run the same B&S V-Twin over 2200 hours on my 1992 Grasshopper. Just my opinion but it works for me.