I am not into Trials, beyond marveling at what a competent trials rider can do on a bicycle, but I thought you might want to take a look at Mountain Goat's contribution to frame design in this realm circa 1986.
Click any image to super-size. My other blog is here: http://blogericious.blogspot.com/ First Flight Bikes is proudly carrying on the Mountain Goat Tradition: http://www.firstflightbikes.com/newgoat.htm