There's SOME truth in that.
The 125 MAY or MAY NOT teach you to ride properly, however, it also teaches you to be WFO most of the time, unless you are weighing in at 100 lbs. That's the difference in the two bikes. With the 250, you have the power on reserve, wherever, and whenever you need it, if you weigh in over 150.
On the 125, I found I had to be in the peak of the power band all the time to do what I wanted to do, and when it came to hill climbs, it did'nt matter, the power wasn't there. Also with technical sections, where there was a neeed for low end power. If I weighed 90 lbs. I would have done fine on the 125, but at my weight, the 250 is a must.
Just my experience.
I look back on that time I rode a 125 that I was thinking about buying, and had some fun on it, but it was way to under powered. But then again, that was in some pretty tight wooded hills. You can whip around the 125 pretty well, but once you get used to the 250 power, you can whip it around pretty well too. I wouldn't trade the power, again, for anything else.
RoosteR
I love the smell of two-stroke in the morning.....