Bigger wheels = easier to push. I have a Sun mountain 3 wheel and a Sun Mountain 4 wheel. The 3 is easier to push even though its about 8lbs heavier (is an older steel tubed model). One time at a course in Denver decided to play par 3 course after doing 18 in a riding cart. So rented a pull cart and it had 27in bicycle wheels. It pulled like a feather despite being a really heavy duty rental at public course. I was amazed at how easily it pulled. Nothing like that currently on the market, but it reallly drove home the point that larger wheels roll easier.
My three wheeler pulls better if you hitch a lift in a riding cart (i.e. storm coming). Tried that twice with the 4 wheeler and it tipped over both times. Never have tipped the 3 wheeler.