We have a pool so the disposables would get expensive for the amount of time we are in the pool.  Plus, the disposables start at size 3/4 and that wouldn't keep anything in since it's too big.  The Swim Diaper has been great and getting a lot of use this year!  It easy enough to rinse and hang out to dry and then I throw in in the washer a couple times a week and then air dry.  It's a big money saver.