Well, i've found that most people under the age of 25 cancel very quickly and use the service as much as possible in the space of time they have, while older people tend to rebill without warrying, and at the same time log into the members area on more regular basis, eg: 2 to 3 times/week and they also download smaller amounts at a time... Just a trend I noticed
Also, most checking account payments cancel their rebills after the first charge, and the ones who dont usually have their check bounce
As for the credit/debit, I don't really have a way of checking it with my payment processor so can't help you there mate.