Are you sure it was the rolling resistance of the small wheels? They personally haven't struck me as being lacking in efficiency and I feel there is a tendency to attribute differences in ride to wheel size, simply because different wheel size changes the way a bike looks so much (ie "the biggest difference in feel must correspond to the biggest difference in look").

I have found that the chain has to be pretty tight to avoid skipping under hard pedaling (ie steep hills) and I believe that may be less efficient. It's hard to say whether this is a problem with the design or if mine just needs a little bit of adjustment because, although I didn't notice either issue when the bike was new, I wasn't riding it as hard when I first got it. Presumably the tugnuts are meant to be adjusted to solve this issue with an appropriate compromise, but right now I have mine way tighter than the "1 inch of play" rule because I'm still learning what the best amount of slack is and what the best technique is for fine tuning.

Although I wish Bruce would comment since I don't consider myself to be very knowledgeable or experienced about bikes in general, but for the record I don't think I would opt to ride 26 miles a day on a Carryme if I could use it multimodally (though I might curious enough to try it), but I also wouldn't do many of the rides lots of people do around here at all.

The more I read this forum the more I see the huge variation in opinions on various bikes. You prefer the Strida to the Brompton and Carryme, Oldiesonfoldies prefers the Carryme and Brompton to the Strida, and I prefer the Carryme to the Tikit. It seems that so much comes down to physiology, riding style, and even the luck of the draw in manufacturing yield/tolerance that it's hard to say what anyone will like until they ride it.