We do not fly IFR and have to get a special transponder code assigned prior to LO. The local tower has been facilitating that for us so there has been very little delay. We advise them of the scene location and probable destination and they coordinate with the approach control center. In flight, we are under constant contact with air traffic controllers. It means more work for the pilot but it hasn't caused significant problems.
We did get cancelled on a call late one night and shortly after turning back we got a visit from a very fast moving object. Not close enough for us to see who it was, but close enough to let us know they were there.