disadvantages of peering with own IP transit customers

Hi, what are the disadvantages of peering(announcing own and all customers prefixes) with own IP transit customers? One disadvantage is obviously that amount of traffic on IP transit link is lower and thus customer pays for smaller amount of Mbps. On the other hand, this can be somewhat compensated with higher price per Mbps if the amount of traffic on the IP transit connection is lower. However, are there any other disadvantages/concerns when peering with own IP transit customers? regards, Martin