I find that at least half of the customers that choose multimonth option do it not because of the value in the deal, but that they don't want to have a recurring membership. they'd rather buy a 3-month membership than have to fool around with cancelling memberships.

i would also think recurring multimonth memberships would lead to chargebacks too. all of a sudden there is a a charge for $70 on their credit card that they haven't seen in 3 months.

i think its best to not be greedy. if they want to continue their membership after it expires they will sign up again.