I've owned 4 challengers
Won't own another one now, was great starter for me. But now use trinity much faster and stronger. Didn't know there were other machines at that time
Challenger machines overheated on me a lot and I kept breaking the motor shafts. I clean a lot of commercial seems to be harder on the machine. And I got sick and tired of the Velcro on the stupid pad driver. Even ordering one from them Velcro would tear away from staples and separate from wood.
The other concern was the ownership of challenger has changed a few times in 7 years