Greg
You may want to spend some time reading on this site about different types of bikes and their purpose. A 125 MX bike is nothing like a TTR125...completely different.
MXGirl
I never said that riding a MX 125 on the trail was impossible, I said that they make poor trail bikes, which is true. If you can ride a 125 MX bike on the trail, just imagine how good you would be on the trail if you had a KDX220. People also define "trails" as different types of terrain.
This guy is asking us which bike to buy and he doesnt know much about bikes. Why would we recommend a MX 125 for trail riding if he could just as easily buy a more trail friendly bike, such as an XR or TTR?