If there is a way for me to acquire and hold on target using standard offhand position (standing, high or low kneeling, sitting or prone), that is my preference. I carry Trek Poles that extend to 155cm which, if you throw each wrist loop over the other pole, give you a stable bipod. I have to crouch to use them standing, but they are more stable than my offhand standing shot: they worked on a pig at 175 yards in July with GSGS.
But check these out: http://www.primos.com/products/trigger-sticks/jim-shockey-tall-tri-pod/
All the guides at Canyon Rim Ranch used them. They are expensive and a little heavy, but they deploy quickly and they completely stabilize your horizontal movement.