I am currently CD'ing my third baby; for about 18mo, a couple years ago, I was CD'ing two kids at once until my oldest potty trained (now kids #1 and #2 are both potty trained). I use CD's about 75% of the time, over night we use disposable diapers (Pamper's FTW!) because we just could not find a CD method that didn't leak, and if the kid did make it through the night, the smell of ammonia in the morning would make our eyes water and it just didn't seem healthy to have urine in contact with the skin for so long.
I have tried a wide variety of diapers and I mainly use Flips and Bumgenius pockets. I also like prefolds with covers (I use Thirsties duo wrap), but it seems like prefolds are more size sensitive baby grows out of them more quickly than the Flip/BG which are more adjustable. I did find that after my second child, the Flip covers were pretty much done, the waterproofing on the inside was cracked and we had lots of leaks, so I bought new covers for baby #3.
At some point, right around 2.5yrs old, we mostly switched back to sposies (I used Earth's Best bought in bulk from Amazon), I don't remember the exact price per diaper, but it wasn't outrageous. Reason for the switch was massive toddler poos - so much not fun with CD's. From about 6mo on I used liners in the diapers, much easier to dispose of the solid waste that way (I shake as much in the toilet as possible from the liner, then throw the liner in the trash), spraying/scraping/dunking diapers is just gross and messy and the liners really helped make the situation tolerable.
I haven't done significant cost comparisons, but considering that some of my diapers have been with me through three children, I would say they have saved us some money, but I definitely don't think that one stash of CD's (whether all in ones, prefolds and covers, China cheapies, pockets, etc) can reasonably be expected to completely last for more that 2 or 3 kids, elastic will give way, waterproofing starts to fail, etc.
For someone considering using CD, I would highly recommend a diaper trial where you can get a variety of different styles and brands to try and return if you don't like them (usually requires a small nonrefundable deposit).
I have no valuable contribution to this thread. Just wanted to throw out there that there is a third alternative. In China, many babies go diaper-less. Their pants have a gap...it's basically two pant legs and a waistband. Grandmas hold their kid up with their tushie hanging down (kind of like making a ring with your arms with the baby sitting in the ring with their bottom in the middle of the ring) and the baby just does his/her business...in the toilet...on the side of the street...in a trash can... Toddlers learn very quickly to squat and go.
Once DH and I were hiking on the Great Wall outside of Beijing (not sure exactly where, but it was a pretty touristy spot) and DH nearly stepped in a pile of poo and says, "who brings their dog here and doesn't clean up after it?!" I was like, "I don't think that is dog poo, dear..."