They were all single seat configurations to conform to FAR103 rules governing ultra-light aircraft. As with most things, this equipment has evolved for the better. The safety margin has increased with the growth of the industry. New machines are more powerful and more reliable with typical motors in the 60-70 hp range. The popular engines are now water cooled for better performance and reliability.
Props are now adjustable and made of composite materials.
Parachutes or canopies are easier to inflate and control. The color schemes are all chosen by you to your taste. The canopies can be chosen by their flight characteristics and consumers now have a choice to fit their preference for the type of flying they will be doing. The cart frames have become stronger, safer and more comfortable. The carts now have a suspension system with larger amounts of travel for difficult landings with new pilots.