CEF Load balancing...

Question (kinda operational).. I've been looking/asking around, but have yet been able to get the same answer twice to the following question: How many links can you have in parallel when using CEF load-sharing per-packet? Another words, we currently have a site that has four DS1s load balanced, in parallel (terminating in the same router on each end). Can you add a [5th|6th|7th|8th] ? Before you answer "BUY A DS3!", this is located in a rural area that a) really doesn't (easily) even have DS3 capabilites, and b) isn't cost effective to have a DS3 as it is about 15 times the cost of a DS1. Thanks for any insight!