I've owned a MK2 Kitfox for 12 years and almost 1000 hours.
I kept it in a trailer and folded its wings after every flight for the first three years. I have an extra support that fits between the fuselage and the forward spar where the pin fits. This takes the weight off the hinge when the wings are folded. It also helps if the wing tanks are empty. Its not a problem for me as I have the large fuselage tank and two wing tanks but it can be if you only have a small fuselage tank.
If the wing tanks are more than about 2/3 full and the wings are folded then the fuel can leak out through the filler caps!
Overall its a great little aircraft but a good check-out is essential. I cruise at 80 mph on a 582 burning about 17 litres/hr. Its climbs at 700 fpm at MTOW and 1400 fpm solo. The flaps are not needed because in a good slip 1500 fpm down is no problem and the landing roll is never more than about 50 metres!
I can't say much about the Avid as I've only flown one, fitted with a Jabiru and a horrible nose-wheel.