The Revos actually have a pretty rigid chassis, with bends in them that add to their resistance to flex. That's why the electric motor mount for the Revo works. With an 1/8 scale buggy, you really don't want to mount the electric motor in nitro motor fashion, because of chassis flex.

Of course, some chassises flex more than others, but, in any case, chassis flex can be very bad for your pinion and spur. Generally speaking, a motor mount that is either bolted to the center diff bulk or incorporates the center diff bulk is the best way to go. That way, the motor and center diff move as one unit.