While the 150 is fun, it isn't efficient. When Cessna put the back window in it in around 1965 or '66, the sharp drop behind the cabin made more drag and slowed the airplane down and probably hurt the climb rate, too. Old straight-tail 150s cruised faster. We gave up on 150s years ago, for two reasons:
1. The t/o and climb at our summertime DA was really rotten, and a student spent all his time climbing. Three circuits an hour, maybe, instead of six in a 172. Might get one spin in a hour's practice, as it would take too long to climb back up for another. Pushing on the ceiling or blowing on the windshield did nothing to help, either
Students spent more money learning to fly because of it.
2. The O-200 has a history of exhaust valve troubles, and we were forever taking cylinders off to fix them. The 150s ended up costing us a much per hour to operate as the 172s.
We also had an O-200-powered Champ 7EC. Exactly the same engine. It carried about the same load. It took off shorter, climbed faster, and cruised faster than the 150s. Much more fun, and the students learned to use their feet. They loved it. But, being a taildragger, it was only for
real pilots...
Dan