Hey birddog, I am not saying that that c-152 is a bad trainer. Is has it's ranks in the training business. However I believe that the 172 is simply a better suited aircraft. As far as being unsafe try taking a 15 year old 152 off from a 4000 ft. strip in the dead of summer with 60 ft. obstacles at the end of the runway. Now for a seasoned pilot this shouldn't pose a problem, but for a student soloing I like a little more leway. A little more horsepower means a little more insurance. Also add better forward visibility, longer range for those solo x/c ies and better stall characteristics are just a few of the other advantages I can think of. I did all of my initial training in a 152 and have logged over 400hr in each type. AS an instructor you feel a lot of responsibitiy for your students, and I always feel better when they depart in a 172 vs. 152.