You dont HAVE to spar anyone man. If you dont feel comfortable, just say no. But it would be a good learning experience. For example, I've been boxing for a little less than a month. Last week, I got into the ring with a former Golden Gloves State Champ, 25 pounds heavier than me, who's been boxing for years..... Didnt get nervous a bit. However, I got my ass handed to me. He caught me with a good uppercut when I let my jab hang out too long. Put me down to one knee on the canvas, and my jaw still hurts. But I took it as a learning experience. I've sparred 3 times since then, and needless to say, I bring my jab right back to guard position every time now.

Also, if this guy is experienced as you say, he should understand your level of boxing ability, and act accordingly. Unless he's some kinda "prick"