I highly recommend being transponder equipped, especially if near busy airspace. I talk to Knoxville approach (TYS) quite regular with my ASW20c, and often am cleared direct thru their Class C to get to back home towards the end of the day. Several times have flown directly over the TYS airport getting home. They are very cooperative. Think it gives the controllers a bit of a changeup from dealing with the repetitious power traffic. Had the same experience with Nashville and Chattanooga. Often they just give a discrete squawk and leave me alone, while pointing the glider out to the other aircraft. And the transponder keeps the heavy iron away...with or without ATC... Adding ADS-B out soon to the T22.