So my overall conclusion to the Flats Challenge? Just Use Prefolds. There's a reason that mamas years ago switched from flats to prefolds. I've been giving lots of commentary on my experience using flats, so I won't reiterate all of that. What I want to use this post for is an analysis of the use of prefolds versus flats.
The initial motivation for the Flats and Handwashing Challenge was that some parents are letting their babies sit in disposables for many hours to save the number of diapers used/purchased, to save money. The idea was that even parents trying to seriously pinch pennies could be successful cloth diapering by using flats and handwashing them.
My argument is that by using prefolds rather than flats, you still have the same capability of cloth diapering your child to save money, you are still able to handwash and hang-to-dry, but you don't have to endure the drawbacks of flat diapers.
A package of 10 flats would have cost me around $14. I'm not taking into account the specials offered for mamas participating in this meme, since any other month of the year, those specials might not be available. They wouldn't have been available to me when I was expecting. I'm basing that price on what they cost at my local discount store, or what they would cost including shipping to order online. I started the challenge with 30 flats but given that we had to change diapers hourly at times, I really needed about 40 flats to truly go three days between washing, which is my preferred schedule.
Meanwhile, when we use prefolds, I can get by with two dozen or less in three days. I have a dozen GMD reds, I have a dozen cheap prefolds (not the polyfill stuffed ones, but the thin cotton ones.) Total cost of those two dozen prefolds: $52. Total cost of 40 flats? $52.
Econobum advertises that you can cloth diaper your baby for $99. (That includes the covers, not mentioned in the cost analysis above, and includes prefolds that are thicker than the cheap prefolds mentioned, and not quite as thick, but softer, than the GMD reds.) If I was a mama starting out with very little money to spend on diapers, I would ask for people to buy me Econobum packages and seconds and use that as the diaper stash. The econobum line is definitely the way to go for quality prefolds and covers offered in packages. If you're buying on your own, GMD and Little Lions prefolds are high quality, and Thirsties covers can't be beat. It's hard to get that stuff as gifts when you have to buy from different place and buy them separately, though.
Handwashing and Hanging to Dry:
Part of the meme was to use flats because they are reportedly easy to hand wash and hang dry. Some mamas might not have access to a convenient washer/dryer and might not want to wash cloth diapers at the laundromat. Handwashing is a pain no matter what kind of diapers you are washing. Personally, I would sink rinse and still bite it to get to washer some way, some how. And that comes from years of apartment living with only a single washer to a building, or a laundromat as an option. I will admit, the drying time for the flats was less than the drying time for the prefolds. Its because they hold less moisture. The cotton prefolds dried faster than the hemp prefolds. Again, because they hold less moisture. Just because flats dry easy does not make them the ideal diaper choice.
Fit and Absorbency:
Flats are thinner than prefolds. That means covers designed for use with prefolds don't fit as well. That means the diapers aren't nearly as absorbent. That is supposed to mean that they will dry faster if you hand wash and hang to dry (see above). So as a mama, you have to decide: which is more important? 30 minutes of faster drying time? Or not having to change a diaper every single hour of your day?
Ease of Use:
They're tied here. I used them both just folded up in a cover. The prefold I trifolded and put in the cover. The flat I folded twice lengthwise and laid in the cover, then folded the excess into a good spot to catch the pee when I fastened the cover. That makes a few more folds for the flat, but I think you're getting too much into semantics there. I'd call them matched, because they're both very easy to use in a cover. Also, I think prefolds have won out in the other categories so I don't need to be that detailed to prove my point.
I think the meme was helpful to create awareness about cloth diapering as a viable option for lower income families. I think the meme was helpful to point out ways that flat diapers can be used for certain ages of babies. Personally, I don't see much of an advantage over prefolds - cost is similar, ease of use is similar, drying time may be better for flats, but you're diaper changing every hour because of the decreased absorbency. If I was advising a penny-pinching mama, I'd tell her prefolds and covers all the way.