Yeah it seems like the "fancier" diapers are most prone to buildup (is this true???), and this just isn't helped by the more water-efficient front loading washers. By "fancier" I mean (especially) diapers with a "stay dry" layer of microfleece, and then really any fitted type of diaper with lots of layers sewn together. It's harder to get all those layers clean, and they take longer to dry, too!
I don't want any moms to think that having a front loader is the final nail in the coffin on your CDing dreams!! I've always used coin-op machines in apartment buildings, and the machines have always been front loaders. Flats have been a godsend for me, for sure. I've NEVER had to use more than one regular wash cycle to get my flats clean.
My secret: I've always rinsed poop off diapers in the bathtub (I know that most people just put the BF poop straight in the machine, but I feel that this is only realistic if you're able/willing to run multiple rinse cycles. I also feel that it's a kindness to my neighbors to keep poop out of shared machines.). Wring the water out and throw the diaper in the wetbag. More solid poop can be plopped into the toilet to avoid the rinsing thing, and a flushable diaper liner is a nice addition IF your kid poops at a predictable time each day. Anyway, I then just run a normal wash cycle with hot water and a scoop of Charlie's or a scant cap of Biokleen laundry liquid.
Yeah, washing the BF poop off diapers in the tub is gross... But I prefer it over doing multiple washloads (my old building in NYC was $1.90/load!!!) and/or getting eventual buildup issues!!!