One way -

My e-tec 175 trolls down just fine...Been using it as my only motor for 3 years now. No problems. They are designed to automatically change how they run at low speed. They sip fuel and burn very little oil at low rpms. You also won't find much difference in fuel economy between the new 2 strokes and the 4 strokes - look at the performance reports. Differences you will find are less weight and higher torque for jumping up on step with a 2 stroke. They are all good motors, just wanted to set a few things straight. Do your homework and good luck.