I agree da Rock,
It has been established well before RC took-off in masses. Full scale gliders do not do well with power planes as well. In case a full scale glider will show-up at JFK vicinity it will have priority for landing over 747 or A-380 and that where money will start leaking like hell.
The same goes for RC fields. But in good community there is always a room for all kind of activity. Like I've mentioned above if flights are on idle - DLG is not an obstruction and could be very enjoyable by onlookers.
I personally would not fly any glider or power plane when someone requested a flight of, say big scale plane before me. I'd rather enjoy watching first and fly later.
People are different and pilots are different. Some can not judge the distance, some have slower reaction. But after all we're all on the field to enjoy the activity and keep our "toys" in one piece.
DLG is not a culprit - ignorance and lack of discipline are.
Happy flying everybody!
Mark.