Yes I have and I LOVE IT!
My first baby I read about it while pg and started when the baby was 6 wks old. He was fully potty trained by 24 months.
With my second baby I got lazy (didn't think I had time to keep taking a newborn to the potty with a toddler underfoot etc)...so this baby was basically in diapers...then around 18 mo I started with the potty training...well DS was not about to change his routine of poop in his pants...tried again at 24 months...finally 2.5 yr i got babylegs and had him going pretty well during the day (with no pants on)..but he wasn't fully trained until 3.5 almost 4.
Then third baby I started with the EC when he was a week old (after all the meconium/tar poop was gone). I would notice he'd get one poop diaper, then I'd change it and within 10 min he'd poop again...change...then third poop 15 min later.... So instead I started taking him EC...he'd have one poop...couple minutes another poop...couple minutes a blow-out farty poop! lol but at least he'd get it all out. By the time he was 2 wks old I was down to 4 diapers per day. He pooped like clockwork when I took him 8 am, 1 pm, 6 pm, 11 pm...i never had to deal with another poop diaper (at home) ever again... seriously he was my best EC baby probably b/c i started so early. He also was much more contented and quieter and happy all around.
It makes perfect sense. I don't know if anyone ever had an accident in their pants but it actually happened to me once when I was pregnant (long story)...and the feeling was absolutely disgusting
The feeling of crap in my pants was enough to stop the bowels... it was a lightbulb moment for me b/c I realized that babies probably feel the same way and that's why they have so many start/stop poops. A normal poop over the toilet you completely clean out the bowels and feel better with less cramps.
Anyhow, if anyone has any EC questions you can feel free to PM me.