I have done some Observed Trials (I was no good) and this bike would have worked some for that. You cannot expect a motor to withstand too much shock from jumping 10 ft drops and what not. The balance is very good and I did not find it much different from my HT bike except for less power. I did braze the rack onto the frame so there was no shifting of the motor. I actually got to watch Hans Rey do some show stuff at a Bike show in Long Beach back in 1985 or so. He could ride up and down and across anything with his trials bikes...
I would never (almost) say never, so go for it if you are good at balance and strength. You really need a solid mounted motor and extra strong frame and parts to make this work.
LennyHarp of Lenny's Bikes & Things
The true value of a man is not judged by what he has, but rather by what he can do without.
"We are what we repeatedly do. Excellence, then, is not an action, but a habit." -- Aristotle