Another zip-leg pants user here. I'm in shorts 80+% of the time and yes, I do change them on the go. The pants part are a necessity if I hit a patch of stinging nettles but bugs are seldom an issue. In really cold weather I have a pair of Arborwear Tech pants I love. I never wear long underwear - my legs get too hot - it would have to be -20°F for me to wear them.