I have a 4 year old girl who wipes herself but she always poops little hard nuggets and has only once had to change her underwear due to insufficient wiping this year. Thankfully, my 4 year old boy is a night time pooper. It's much more preferable to the 3 1/2 year old girl who went off to JK last Sept. still pooping in her pullups. That was HORRIBLE!
I did buy those flushable wipes and they are in my bathroom in case I ever have a child who can use those while they learn. I think they are a great idea.