It's always better to take a rest, take a rest, take a rest. Most hunters don't get to practice firing thier rifle the hundreds of times it would take to be very effective in off hand shooting past 100 yards. Some shooting sticks fold down and can be carried in a pack on your belt, much like a knife. You hardly notice you have them.
I prefer shooting sticks over the gun mounted bi-pods for several reasons. BUT either way is better than off hand in most situations!