Load balancing is a funny stuff. Its utility is very limited
by the fact that you've got to keep packets in sequence to
avoid triggering TCP fast retransmits.
I.e. with ciscos you can only do load-balancing on paths
(i.e. load one circuit with traffic to ISP A and another to ISP B
etc) or on destination networks (that has a potential of causing
very skewed load distribution).
I admit I'm not familiar with the impact of 'ip route-caching'
tens of thousands of equal-cost paths at dual-HSSI speed. I was
told by some at Cisco that it wouldn't be a problem.
Before i left Sprint i produced a plan for them to increase
capacity at least four-fold using combination of load balancing
and hot-potato intra-backbone routing. Going to OC-3s is
a lot simplier, though
True, it's simpler - but one does what one needs to do to stay
alive. Or one should, at least