Advantages

No no ...not a bi-plane!

Due to its construction method of foam and glassfibre-epoxy it is rather easy to make.
Due to its tandem wings it has the typical tandem stability.
Althought the engine only had 18 HP, the Quicky had a maximum speed of 203 km/h (126 mph).
Low fuel consumption (4,54 litres (1 Imp gal.) over 161 km (100 miles) at cruise speed). Quickie flew in August 1978 from Mojave, California to Oshkosh, Winconsin and back. Total of 6780 km (4200 miles). The trip costed only $55 in fuel and oil!
I guess that the reason for this outstanding performance is caused by very smooth lines (low drag), a smooth finish (typical for this kind of composites construction) and a low weight (empty weight 109 kg (240 lb)).