An airspeed event will definately help, no matter what your ability level, especially in the tunnel. Alternatives do, exitst, however and offer equally as good a coaching (Doug Park and Joey Jones come to mind -- they actually pioneered a lot of the tunnel coaching before it became really hot). Airspeed will take you through prep work, and an extensive de-brief of your flying. You'll also spend a fair chunk of change. I just spent 5 hours in teh tunnel this past weekend, with Doug, and it cost me a lot less (made 9 jumps, too) -- I'm WAY sore!
Have you seen airspeed in a video yet. If not go get some then you wouldn't be asking this question. They are unreal (although at 37 jumps almost everyone seems that way) I saw them in crosswind and I wish I could move at a 1000th of their speed (slow is fast). I watched them frame by frame and their body control is awesome I bet you would get better just by touching them.