I stood in for about five rounds with three different people; one person larger, similar and smaller in size to me. Being new to this class I tried to keep it really light, and really controlled, nobody likes the new sparring guy who wants to brawl. My biggest mistake was not blocking kicks to the outside of my left thigh with the big guy, hence the sore leg. I took a few round kicks to my torso also, and that's why they have us do lots of situps in the regular class.
I had fun, but didn't make it to the end. I was tired and hungry, and didn't have much energy after being at the gym for two hours before the class started. I am looking forward to the next time, and hopefully doing a little better.